Almkvist-Giullera formula for pi

From Rosetta Code
Revision as of 20:11, 15 January 2022 by rosettacode>VincentArm (add task to aarch64 assembly raspberry pi)
Task
Almkvist-Giullera formula for pi
You are encouraged to solve this task according to the task description, using any language you may know.

The Almkvist-Giullera formula for calculating   1/π2   is based on the Calabi-Yau differential equations of order 4 and 5,   which were originally used to describe certain manifolds in string theory.


The formula is:

1/π2 = (25/3) ∑0 ((6n)! / (n!6))(532n2 + 126n + 9) / 10002n+1


This formula can be used to calculate the constant   π-2,   and thus to calculate   π.

Note that, because the product of all terms but the power of 1000 can be calculated as an integer, the terms in the series can be separated into a large integer term:

(25) (6n)! (532n2 + 126n + 9) / (3(n!)6)     (***)

multiplied by a negative integer power of 10:

10-(6n + 3)


Task
  • Print the integer portions (the starred formula, which is without the power of 1000 divisor) of the first 10 terms of the series.
  • Use the complete formula to calculate and print π to 70 decimal digits of precision.


Reference



11l

Translation of: C#

<lang 11l>F isqrt(BigInt =x)

  BigInt q = 1
  BigInt r = 0
  BigInt t
  L q <= x
     q *= 4
  L q > 1
     q I/= 4
     t = x - r - q
     r I/= 2
     I t >= 0
        x = t
        r += q
  R r

F dump(=digs, show)

  V gb = 1
  digs++
  V dg = digs + gb
  BigInt t1 = 1
  BigInt t2 = 9
  BigInt t3 = 1
  BigInt te
  BigInt su = 0
  V t = BigInt(10) ^ (I dg <= 60 {0} E dg - 60)
  BigInt d = -1
  BigInt _fn_ = 1
  V n = 0
  L n < dg
     I n > 0
        t3 *= BigInt(n) ^ 6
     te = t1 * t2 I/ t3
     V z = dg - 1 - n * 6
     I z > 0
        te *= BigInt(10) ^ z
     E
        te I/= BigInt(10) ^ -z
     I show & n < 10
        print(‘#2 #62’.format(n, te * 32 I/ 3 I/ t))
     su += te
     I te < 10
        I show
           digs--
           print("\n#. iterations required for #. digits after the decimal point.\n".format(n, digs))
        L.break
     L(j) n * 6 + 1 .. n * 6 + 6
        t1 *= j
     d += 2
     t2 += 126 + 532 * d
     n++
  V s = String(isqrt(BigInt(10) ^ (dg * 2 + 3) I/ su I/ 32 * 3 * BigInt(10) ^ (dg + 5)))
  R s[0]‘.’s[1 .+ digs]

print(dump(70, 1B))</lang>

Output:
 0  9600000000000000000000000000000000000000000000000000000000000
 1   512256000000000000000000000000000000000000000000000000000000
 2    19072247040000000000000000000000000000000000000000000000000
 3      757482485760000000000000000000000000000000000000000000000
 4       31254615037245600000000000000000000000000000000000000000
 5        1320787470322549142065152000000000000000000000000000000
 6          56727391979308908329225994240000000000000000000000000
 7           2465060024817298714011276371558400000000000000000000
 8            108065785435463945367040747443956640000000000000000
 9              4770177939159496628747057049083997888000000000000

53 iterations required for 70 digits after the decimal point.

3.1415926535897932384626433832795028841971693993751058209749445923078164

AArch64 Assembly

Works with: as version Raspberry Pi 3B version Buster 64 bits
or android 64 bits with application Termux

<lang AArch64 Assembly> /* ARM assembly AARCH64 Raspberry PI 3B */ /* program calculPi64.s */ /* this program use gmp library */ /* link with gcc option -lgmp */

/*******************************************/ /* Constantes file */ /*******************************************/ /* for this file see task include a file in language AArch64 assembly*/ .include "../includeConstantesARM64.inc"

.equ MAXI, 10 .equ SIZEBIG, 100

/*********************************/ /* Initialized data */ /*********************************/ .data szMessDebutPgm: .asciz "Program 64 bits start. \n" szMessPi: .asciz "\nPI = \n" szCarriageReturn: .asciz "\n"

szFormat: .asciz " %Zd\n" szFormatFloat: .asciz " %.*Ff\n" /*********************************/ /* UnInitialized data */ /*********************************/ .bss Result1: .skip SIZEBIG Result2: .skip SIZEBIG Result3: .skip SIZEBIG Result4: .skip SIZEBIG fIntex5: .skip SIZEBIG fIntex6: .skip SIZEBIG fIntex7: .skip SIZEBIG fSum: .skip SIZEBIG fSum1: .skip SIZEBIG sBuffer: .skip SIZEBIG fEpsilon: .skip SIZEBIG fPrec: .skip SIZEBIG fPI: .skip SIZEBIG fTEN: .skip SIZEBIG fONE: .skip SIZEBIG /*********************************/ /* code section */ /*********************************/ .text .global main main: // entry of program

   ldr x0,qAdrszMessDebutPgm
   bl affichageMess
   mov x20,#0                     // loop indice

1:

   mov x0,x20
   bl computeAlmkvist            // compute 
   mov x1,x0
   ldr x0,qAdrszFormat           // print big integer
   bl __gmp_printf
   
   add x20,x20,#1
   cmp x20,#MAXI
   blt 1b                        // and loop
   
   mov x0,#560                   // float précision in bits
   bl __gmpf_set_default_prec
   
   mov x19,#0                     // compute indice
   ldr x0,qAdrfSum               // init to zéro
   bl __gmpf_init
   ldr x0,qAdrfSum1              // init to zéro
   bl __gmpf_init
   
   ldr x0,qAdrfONE               // result address
   mov x1,#1                     // init à 1
   bl __gmpf_init_set_ui
   
   ldr x0,qAdrfIntex5            // init to zéro
   bl __gmpf_init
   ldr x0,qAdrfIntex6            // init to zéro
   bl __gmpf_init
   ldr x0,qAdrfIntex7            // init to zéro
   bl __gmpf_init
   ldr x0,qAdrfEpsilon           // init to zéro
   bl __gmpf_init
   ldr x0,qAdrfPrec              // init to zéro
   bl __gmpf_init
   ldr x0,qAdrfPI                // init to zéro
   bl __gmpf_init
   ldr x0,qAdrfTEN
   mov x1,#10                    // init to 10
   bl __gmpf_init_set_ui
   
   ldr x0,qAdrfIntex6            // compute 10 pow 70
   ldr x1,qAdrfTEN
   mov x2,#70
   bl __gmpf_pow_ui
   
   ldr x0,qAdrfEpsilon           // divide 1 by 10 pow 70
   ldr x1,qAdrfONE               // dividende
   ldr x2,qAdrfIntex6            // divisor
   bl __gmpf_div
   

2: // PI compute loop

   mov x0,x19
   bl computeAlmkvist
   mov x20,x0
   mov x1,#6
   mul x2,x1,x19
   add x6,x2,#3                  // compute 6n + 3
   
   ldr x0,qAdrfIntex6            // compute 10 pow (6n+3)
   ldr x1,qAdrfTEN
   mov x2,x6
   bl __gmpf_pow_ui
   
   ldr x0,qAdrfIntex7             // compute 1 / 10 pow (6n+3)
   ldr x1,qAdrfONE                // dividende
   ldr x2,qAdrfIntex6             // divisor
   bl __gmpf_div
   
   ldr x0,qAdrfIntex6             // result big float
   mov x1,x20                     // big integer Almkvist
   bl __gmpf_set_z                // conversion in big float
   
   ldr x0,qAdrfIntex5             // result Almkvist * 1 / 10 pow (6n+3)
   ldr x1,qAdrfIntex7             // operator 1
   ldr x2,qAdrfIntex6             // operator 2
   bl __gmpf_mul
   
   ldr x0,qAdrfSum1               // terms addition
   ldr x1,qAdrfSum
   ldr x2,qAdrfIntex5
   bl __gmpf_add
   
   ldr x0,qAdrfSum                // copy terms
   ldr x1,qAdrfSum1
   bl __gmpf_set
   
   
   ldr x0,qAdrfIntex7             // compute 1 / sum 
   ldr x1,qAdrfONE                // dividende
   ldr x2,qAdrfSum                // divisor
   bl __gmpf_div
   
   ldr x0,qAdrfPI                 // compute square root (1 / sum )
   ldr x1,qAdrfIntex7
   bl __gmpf_sqrt
   
   ldr x0,qAdrfIntex6             // compute variation PI
   ldr x1,qAdrfPrec
   ldr x2,qAdrfPI
   bl __gmpf_sub
   
   ldr x0,qAdrfIntex6             // absolue value
   ldr x1,qAdrfIntex5
   bl __gmpf_abs
   
   add x19,x19,#1                   // increment indice
   
   ldr x0,qAdrfPrec               // copy PI -> prévious
   ldr x1,qAdrfPI
   bl __gmpf_set
       
   ldr x0,qAdrfIntex6             // compare gap and epsilon
   ldr x1,qAdrfEpsilon
   bl __gmpf_cmp
   cmp w0,#0                      // !!! cmp return result on 32 bits
   bgt 2b                         // if gap is highter -> loop
   
   ldr x0,qAdrszMessPi            // title display
   bl affichageMess
   
   ldr x2,qAdrfPI                 // PI display
   ldr x0,qAdrszFormatFloat
   mov x1,#70
   bl __gmp_printf
   

100: // standard end of the program

   mov x0, #0                    // return code
   mov x8, #EXIT                 // request to exit program
   svc #0                        // perform the system call

qAdrszMessDebutPgm: .quad szMessDebutPgm qAdrszCarriageReturn: .quad szCarriageReturn qAdrfIntex5: .quad fIntex5 qAdrfIntex6: .quad fIntex6 qAdrfIntex7: .quad fIntex7 qAdrfSum: .quad fSum qAdrfSum1: .quad fSum1 qAdrszFormatFloat: .quad szFormatFloat qAdrszMessPi: .quad szMessPi qAdrfEpsilon: .quad fEpsilon qAdrfPrec: .quad fPrec qAdrfPI: .quad fPI qAdrfTEN: .quad fTEN qAdrfONE: .quad fONE /***************************************************/ /* compute almkvist_giullera formula */ /***************************************************/ /* x0 contains the number */ computeAlmkvist:

   stp x19,lr,[sp,-16]!           // save  registers
   mov x19,x0
   mov x1,#6
   mul x0,x1,x0
   ldr x1,qAdrResult1            // result address
   bl computeFactorielle         // compute (n*6)!
   mov x1,#532
   mul x2,x19,x19
   mul x2,x1,x2
   mov x1,#126
   mul x3,x19,x1
   add x2,x2,x3
   add x2,x2,#9
   lsl x2,x2,#5                   // * 32
   
   ldr x0,qAdrResult2             // result
   ldr x1,qAdrResult1             // operator
   bl __gmpz_mul_ui
   
   mov x0,x19
   ldr x1,qAdrResult1 
   bl computeFactorielle
   
   ldr x0,qAdrResult3
   bl __gmpz_init                 // init to 0
   
   ldr x0,qAdrResult3             // result
   ldr x1,qAdrResult1             // operator
   mov x2,#6
   bl __gmpz_pow_ui
   
   ldr x0,qAdrResult1             // result
   ldr x1,qAdrResult3             // operator
   mov x2,#3
   bl __gmpz_mul_ui
   
   ldr x0,qAdrResult3             // result
   ldr x1,qAdrResult2             // operator
   ldr x2,qAdrResult1             // operator
   bl __gmpz_cdiv_q
   
   ldr x0,qAdrResult3             // return result address

100:

   ldp x19,lr,[sp],16              // restaur  2 registers
   ret                            // return to address lr x30

qAdrszFormat: .quad szFormat qAdrResult1: .quad Result1 qAdrResult2: .quad Result2 qAdrResult3: .quad Result3 /***************************************************/ /* compute factorielle N */ /***************************************************/ /* x0 contains the number */ /* x1 contains big number result address */ computeFactorielle:

   stp x19,lr,[sp,-16]!           // save  registers
   stp x20,x21,[sp,-16]!           // save  registers
   mov x19,x0                     // save N
   mov x20,x1                     // save result address
   mov x0,x1                     // result address
   mov x1,#1                     // init to 1
   bl __gmpz_init_set_ui
   ldr x0,qAdrResult4
   bl __gmpz_init                // init to 0
   mov x21,#1

1: // loop

   ldr x0,qAdrResult4            // result
   mov x1,x20                     // operator 1
   mov x2,x21                     // operator 2
   bl __gmpz_mul_ui
   mov x0,x20                     // copy result4 -> result 
   ldr x1,qAdrResult4
   bl __gmpz_set
   add x21,x21,#1                  // increment indice
   cmp x21,x19                     // N ?
   ble 1b                        // no -> loop
   
   ldr  x0,qAdrResult4
   ldp x20,x21,[sp],16              // restaur  2 registers
   ldp x19,lr,[sp],16              // restaur  2 registers
   ret                            // return to address lr x30

qAdrResult4: .quad Result4 /********************************************************/ /* File Include fonctions */ /********************************************************/ /* for this file see task include a file in language AArch64 assembly */ .include "../includeARM64.inc" </lang>

Program 64 bits start.
 96
 5122560
 190722470400
 7574824857600000
 312546150372456000000
 13207874703225491420651520
 567273919793089083292259942400
 24650600248172987140112763715584000
 1080657854354639453670407474439566400000
 47701779391594966287470570490839978880000000

PI =
 3.1415926535897932384626433832795028841971693993751058209749445923078164

ARM Assembly

Works with: as version Raspberry Pi
or android 32 bits with application Termux

<lang ARM Assembly> /* ARM assembly Raspberry PI */ /* program calculPi.s */ /* this program use gmp library package : libgmp3-dev */ /* link with gcc option -lgmp */

/* REMARK 1 : this program use routines in a include file 
  see task Include a file language arm assembly 
  for the routine affichageMess conversion10 
  see at end of this program the instruction include */

/* for constantes see task include a file in arm assembly */ /************************************/ /* Constantes */ /************************************/ .include "../constantes.inc"

.equ MAXI, 10 .equ SIZEBIG, 100

/*********************************/ /* Initialized data */ /*********************************/ .data szMessPi: .asciz "\nPI = \n" szCarriageReturn: .asciz "\n"

szFormat: .asciz " %Zd\n" szFormatFloat: .asciz " %.*Ff\n" /*********************************/ /* UnInitialized data */ /*********************************/ .bss Result1: .skip SIZEBIG Result2: .skip SIZEBIG Result3: .skip SIZEBIG Result4: .skip SIZEBIG fInter5: .skip SIZEBIG fInter6: .skip SIZEBIG fInter7: .skip SIZEBIG fSum: .skip SIZEBIG fSum1: .skip SIZEBIG sBuffer: .skip SIZEBIG fEpsilon: .skip SIZEBIG fPrec: .skip SIZEBIG fPI: .skip SIZEBIG fTEN: .skip SIZEBIG fONE: .skip SIZEBIG /*********************************/ /* code section */ /*********************************/ .text .global main main: @ entry of program

   mov r4,#0                     @ loop indice

1:

   mov r0,r4
   bl computeAlmkvist            @ compute 
   mov r1,r0
   ldr r0,iAdrszFormat           @ print big integer
   bl __gmp_printf
   
   add r4,r4,#1
   cmp r4,#MAXI
   blt 1b                        @ and loop
   
   mov r0,#560                   @ float précision in bits
   bl __gmpf_set_default_prec
   
   mov r4,#0                     @ compute indice
   ldr r0,iAdrfSum               @ init to zéro
   bl __gmpf_init
   ldr r0,iAdrfSum1              @ init to zéro
   bl __gmpf_init
   
   ldr r0,iAdrfONE               @ result address
   mov r1,#1                     @ init à 1
   bl __gmpf_init_set_ui
   
   ldr r0,iAdrfInter5            @ init to zéro
   bl __gmpf_init
   ldr r0,iAdrfInter6            @ init to zéro
   bl __gmpf_init
   ldr r0,iAdrfInter7            @ init to zéro
   bl __gmpf_init
   ldr r0,iAdrfEpsilon           @ init to zéro
   bl __gmpf_init
   ldr r0,iAdrfPrec              @ init to zéro
   bl __gmpf_init
   ldr r0,iAdrfPI                @ init to zéro
   bl __gmpf_init
   ldr r0,iAdrfTEN
   mov r1,#10                    @ init to 10
   bl __gmpf_init_set_ui
   
   ldr r0,iAdrfInter6            @ compute 10 pow 70
   ldr r1,iAdrfTEN
   mov r2,#70
   bl __gmpf_pow_ui
   
   ldr r0,iAdrfEpsilon           @ divide 1 by 10 pow 70
   ldr r1,iAdrfONE               @ dividende
   ldr r2,iAdrfInter6            @ divisor
   bl __gmpf_div
   

2: @ PI compute loop

   mov r0,r4
   bl computeAlmkvist
   mov r5,r0
   mov r1,#6
   mul r2,r1,r4
   add r6,r2,#3                  @ compute 6n + 3
   
   ldr r0,iAdrfInter6            @ compute 10 pow (6n+3)
   ldr r1,iAdrfTEN
   mov r2,r6
   bl __gmpf_pow_ui
   
   ldr r0,iAdrfInter7             @ compute 1 / 10 pow (6n+3)
   ldr r1,iAdrfONE                @ dividende
   ldr r2,iAdrfInter6             @ divisor
   bl __gmpf_div
   
   ldr r0,iAdrfInter6             @ result big float
   mov r1,r5                      @ big integer Almkvist
   bl __gmpf_set_z                @ conversion in big float
   
   ldr r0,iAdrfInter5             @ result Almkvist * 1 / 10 pow (6n+3)
   ldr r1,iAdrfInter7             @ operator 1
   ldr r2,iAdrfInter6             @ operator 2
   bl __gmpf_mul
   
   ldr r0,iAdrfSum1               @ terms addition
   ldr r1,iAdrfSum
   ldr r2,iAdrfInter5
   bl __gmpf_add
   
   ldr r0,iAdrfSum                @ copy terms
   ldr r1,iAdrfSum1
   bl __gmpf_set
   
   
   ldr r0,iAdrfInter7             @ compute 1 / sum 
   ldr r1,iAdrfONE                @ dividende
   ldr r2,iAdrfSum                @ divisor
   bl __gmpf_div
   
   ldr r0,iAdrfPI                 @ compute square root (1 / sum )
   ldr r1,iAdrfInter7
   bl __gmpf_sqrt
   
   ldr r0,iAdrfInter6             @ compute variation PI
   ldr r1,iAdrfPrec
   ldr r2,iAdrfPI
   bl __gmpf_sub
   
   ldr r0,iAdrfInter6             @ absolue value
   ldr r1,iAdrfInter5
   bl __gmpf_abs
   
   add r4,r4,#1                   @ increment indice
   
   ldr r0,iAdrfPrec               @ copy PI -> prévious
   ldr r1,iAdrfPI
   bl __gmpf_set
       
   ldr r0,iAdrfInter6             @ compare gap and epsilon
   ldr r1,iAdrfEpsilon
   bl __gmpf_cmp
   cmp r0,#0
   bgt 2b                         @ if gap is highter -> loop
   
   ldr r0,iAdrszMessPi            @ title display
   bl affichageMess
   
   ldr r2,iAdrfPI                 @ PI display
   ldr r0,iAdrszFormatFloat
   mov r1,#70
   bl __gmp_printf
   

100: @ standard end of the program

   mov r0, #0                    @ return code
   mov r7, #EXIT                 @ request to exit program
   svc #0                        @ perform the system call

iAdrszCarriageReturn: .int szCarriageReturn iAdrfInter5: .int fInter5 iAdrfInter6: .int fInter6 iAdrfInter7: .int fInter7 iAdrfSum: .int fSum iAdrfSum1: .int fSum1 iAdrszFormatFloat: .int szFormatFloat iAdrszMessPi: .int szMessPi iAdrfEpsilon: .int fEpsilon iAdrfPrec: .int fPrec iAdrfPI: .int fPI iAdrfTEN: .int fTEN iAdrfONE: .int fONE /***************************************************/ /* compute almkvist_giullera formula */ /***************************************************/ /* r0 contains the number */ computeAlmkvist:

   push {r1-r4,lr}               @ save registers 
   mov r4,r0
   mov r1,#6
   mul r0,r1,r0
   ldr r1,iAdrResult1            @ result address
   bl computeFactorielle         @ compute (n*6)!
   
   mov r1,#532
   mul r2,r4,r4 
   mul r2,r1,r2
   mov r1,#126
   mul r3,r4,r1
   add r2,r2,r3
   add r2,#9
   lsl r2,r2,#5                   @ * 32
   
   ldr r0,iAdrResult2             @ result
   ldr r1,iAdrResult1             @ operator
   bl __gmpz_mul_ui
   
   mov r0,r4
   ldr r1,iAdrResult1 
   bl computeFactorielle
   
   ldr r0,iAdrResult3
   bl __gmpz_init                 @ init to 0
   
   ldr r0,iAdrResult3             @ result
   ldr r1,iAdrResult1             @ operator
   mov r2,#6
   bl __gmpz_pow_ui
   
   ldr r0,iAdrResult1             @ result
   ldr r1,iAdrResult3             @ operator
   mov r2,#3
   bl __gmpz_mul_ui
   
   ldr r0,iAdrResult3             @ result
   ldr r1,iAdrResult2             @ operator
   ldr r2,iAdrResult1             @ operator
   bl __gmpz_cdiv_q
   
   ldr r0,iAdrResult3             @ return result address
   
   pop {r1-r4,pc}                 @ restaur des registres

iAdrszFormat: .int szFormat iAdrResult1: .int Result1 iAdrResult2: .int Result2 iAdrResult3: .int Result3 /***************************************************/ /* compute factorielle N */ /***************************************************/ /* r0 contains the number */ /* r1 contains big number result address */ computeFactorielle:

   push {r1-r6,lr}               @ save registers 
   mov r5,r0                     @ save N
   mov r6,r1                     @ save result address
   mov r0,r1                     @ result address
   mov r1,#1                     @ init to 1
   bl __gmpz_init_set_ui
   ldr r0,iAdrResult4
   bl __gmpz_init                @ init to 0
   mov r4,#1

1: @ loop

   ldr r0,iAdrResult4            @ result
   mov r1,r6                     @ operator 1
   mov r2,r4                     @ operator 2
   bl __gmpz_mul_ui
   mov r0,r6                     @ copy result4 -> result 
   ldr r1,iAdrResult4
   bl __gmpz_set
   add r4,r4,#1                  @ increment indice
   cmp r4,r5                     @ N ?
   ble 1b                        @ no -> loop
   
   mov r0,r1 
   
   pop {r1-r6,pc}                @ restaur des registres

iAdrResult4: .int Result4

/***************************************************/ /* ROUTINES INCLUDE */ /***************************************************/ .include "../affichage.inc" </lang>

 96
 5122560
 190722470400
 7574824857600000
 312546150372456000000
 13207874703225491420651520
 567273919793089083292259942400
 24650600248172987140112763715584000
 1080657854354639453670407474439566400000
 47701779391594966287470570490839978880000000

PI =
 3.1415926535897932384626433832795028841971693993751058209749445923078164

C#

A little challenging due to lack of BigFloat or BigRational. Note the extended precision integers displayed for each term, not extended precision floats. Also features the next term based on the last term, rather than computing each term from scratch. And the multiply by 32, divide by 3 is reserved for final sum, instead of each term (except for the 0..9th displayed terms). <lang csharp>using System; using BI = System.Numerics.BigInteger; using static System.Console;

class Program {

 static BI isqrt(BI x) { BI q = 1, r = 0, t; while (q <= x) q <<= 2; while (q > 1) {
   q >>= 2; t = x - r - q; r >>= 1; if (t >= 0) { x = t; r += q; } } return r; }

  static string dump(int digs, bool show = false) {

   int gb = 1, dg = ++digs + gb, z;
   BI t1 = 1, t2 = 9, t3 = 1, te, su = 0,
      t = BI.Pow(10, dg <= 60 ? 0 : dg - 60), d = -1, fn = 1;
   for (BI n = 0; n < dg; n++) {
     if (n > 0) t3 *= BI.Pow(n, 6);
     te = t1 * t2 / t3;
     if ((z = dg - 1 - (int)n * 6) > 0) te *= BI.Pow (10, z);
     else te /= BI.Pow (10, -z);
     if (show && n < 10)
       WriteLine("{0,2} {1,62}", n, te * 32 / 3 / t);
     su += te; if (te < 10) {
       if (show) WriteLine("\n{0} iterations required for {1} digits " +
       "after the decimal point.\n", n, --digs); break; }
     for (BI j = n * 6 + 1; j <= n * 6 + 6; j++) t1 *= j;
     t2 += 126 + 532 * (d += 2);
   }
   string s = string.Format("{0}", isqrt(BI.Pow(10, dg * 2 + 3) /
     su / 32 * 3 * BI.Pow((BI)10, dg + 5)));
   return s[0] + "." + s.Substring(1, digs); }
 static void Main(string[] args) {
   WriteLine(dump(70, true)); }

}</lang>

Output:
 0  9600000000000000000000000000000000000000000000000000000000000
 1   512256000000000000000000000000000000000000000000000000000000
 2    19072247040000000000000000000000000000000000000000000000000
 3      757482485760000000000000000000000000000000000000000000000
 4       31254615037245600000000000000000000000000000000000000000
 5        1320787470322549142065152000000000000000000000000000000
 6          56727391979308908329225994240000000000000000000000000
 7           2465060024817298714011276371558400000000000000000000
 8            108065785435463945367040747443956640000000000000000
 9              4770177939159496628747057049083997888000000000000

53 iterations required for 70 digits after the decimal point.

3.1415926535897932384626433832795028841971693993751058209749445923078164

C++

Library: Boost
Library: GMP

<lang cpp>#include <boost/multiprecision/cpp_dec_float.hpp>

  1. include <boost/multiprecision/gmp.hpp>
  2. include <iomanip>
  3. include <iostream>

namespace mp = boost::multiprecision; using big_int = mp::mpz_int; using big_float = mp::cpp_dec_float_100; using rational = mp::mpq_rational;

big_int factorial(int n) {

   big_int result = 1;
   for (int i = 2; i <= n; ++i)
       result *= i;
   return result;

}

// Return the integer portion of the nth term of Almkvist-Giullera sequence. big_int almkvist_giullera(int n) {

   return factorial(6 * n) * 32 * (532 * n * n + 126 * n + 9) /
          (pow(factorial(n), 6) * 3);

}

int main() {

   std::cout << "n |                  Integer portion of nth term\n"
             << "------------------------------------------------\n";
   for (int n = 0; n < 10; ++n)
       std::cout << n << " | " << std::setw(44) << almkvist_giullera(n)
                 << '\n';
   big_float epsilon(pow(big_float(10), -70));
   big_float prev = 0, pi = 0;
   rational sum = 0;
   for (int n = 0;; ++n) {
       rational term(almkvist_giullera(n), pow(big_int(10), 6 * n + 3));
       sum += term;
       pi = sqrt(big_float(1 / sum));
       if (abs(pi - prev) < epsilon)
           break;
       prev = pi;
   }
   std::cout << "\nPi to 70 decimal places is:\n"
             << std::fixed << std::setprecision(70) << pi << '\n';

}</lang>

Output:
n |                  Integer portion of nth term
------------------------------------------------
0 |                                           96
1 |                                      5122560
2 |                                 190722470400
3 |                             7574824857600000
4 |                        312546150372456000000
5 |                   13207874703225491420651520
6 |               567273919793089083292259942400
7 |          24650600248172987140112763715584000
8 |     1080657854354639453670407474439566400000
9 | 47701779391594966287470570490839978880000000

Pi to 70 decimal places is:
3.1415926535897932384626433832795028841971693993751058209749445923078164

Common Lisp

Translation of: Raku

<lang lisp>(ql:quickload :computable-reals :silent t) (use-package :computable-reals) (setq *print-prec* 70) (defparameter *iterations* 52)

factorial using computable-reals multiplication op to keep precision

(defun !r (n)

 (let ((p 1))
   (loop for i from 2 to n doing (setq p (*r p i)))
   p))
the nth integer term

(defun integral (n)

  (let* ((polynomial (+r (*r 532 n n) (*r 126 n) 9))
         (numer  (*r 32 (!r (*r 6 n)) polynomial))
         (denom  (*r 3 (expt-r (!r n) 6))))
   (/r  numer denom)))
     
the exponent for 10 in the nth term of the series

(defun power (n) (- 3 (* 6 (1+ n))))

the nth term of the series

(defun almkvist-giullera (n)

 (/r (integral n) (expt-r 10 (abs (power n)))))
the sum of the first n terms

(defun almkvist-giullera-sigma (n)

 (let ((s 0)) 
   (loop for i from 0 to n doing (setq s (+r s (almkvist-giullera i))))
   s))
the approximation to pi after n terms

(defun almkvist-giullera-pi (n)

 (sqrt-r (/r 1 (almkvist-giullera-sigma n))))

(format t "~A. ~44A~4A ~A~%" "N" "Integral part of Nth term" "×10^" "=Actual value of Nth term") (loop for i from 0 to 9 doing

 (format t "~&~a. ~44d ~3d " i (integral i) (power i))
 (finish-output *standard-output*)
 (print-r (almkvist-giullera i) 50 nil))

(format t "~%~%Pi after ~a iterations: " *iterations*) (print-r (almkvist-giullera-pi *iterations*) *print-prec*) </lang>

Output:
N. Integral part of Nth term                   ×10^ =Actual value of Nth term
0.                                           96  -3 +0.09600000000000000000000000000000000000000000000000...
1.                                      5122560  -9 +0.00512256000000000000000000000000000000000000000000...
2.                                 190722470400 -15 +0.00019072247040000000000000000000000000000000000000...
3.                             7574824857600000 -21 +0.00000757482485760000000000000000000000000000000000...
4.                        312546150372456000000 -27 +0.00000031254615037245600000000000000000000000000000...
5.                   13207874703225491420651520 -33 +0.00000001320787470322549142065152000000000000000000...
6.               567273919793089083292259942400 -39 +0.00000000056727391979308908329225994240000000000000...
7.          24650600248172987140112763715584000 -45 +0.00000000002465060024817298714011276371558400000000...
8.     1080657854354639453670407474439566400000 -51 +0.00000000000108065785435463945367040747443956640000...
9. 47701779391594966287470570490839978880000000 -57 +0.00000000000004770177939159496628747057049083997888...

Pi after 52 iterations: 
+3.1415926535897932384626433832795028841971693993751058209749445923078164...

dc

Translation of: Common Lisp

<lang dc>[* factorial *]sz [ 1 Sp [ d lp * sp 1 - d 1 <f ]Sf d 1 <f Lfsz sz Lp ]sF

[* nth integral term *]sz [ sn 32 6 ln * lFx 532 ln * ln * 126 ln * + 9 + * * 3 ln lFx 6 ^ * / ]sI

[* nth exponent of 10 *]sz [ 1 + 6 * 3 r - ]sE

[* nth term in series *]sz [ d lIx r 10 r lEx _1 * ^ / ]sA

[* sum of the first n terms *]sz [ [li lAx ls + ss li 1 - d si 0 r !<L]sL si 0ss lLx ls]sS

[* approximation of pi after n terms *]sz [ lSx 1 r / v ]sP

[* count digits in a number *]sz [sn 0 sd lCx ld]sD [ld 1 + sd ln 10 0k / d sn 0 !=C]sC

[* print a number in a given column width *]sz [sw d lDx si lw li <T n]sW [[ ]n li 1 + si lw li <T]sT

[* main loop: print values for first 10 terms *]sz [N. Integral part of Nth term .................. × 10^ =Actual value of Nth term]p 0 sj [

 lj n [. ]n
 lj lIx 0k 1 / 44 lWx [ ]n
 lj lEx 4 lWx [ ]n
 lj 99k lAx 50k 1 / p
 lj 1 + d sj 10 >M

] sM lMx

[]p

[* print resulting value of pi to 70 places *]sz [Pi after ]n 52n [ iterations:]p 99k 52 lPx 70k 1 / p</lang>

Output:
N. Integral part of Nth term .................. × 10^ =Actual value of Nth term
0.                                           96    -3 .09600000000000000000000000000000000000000000000000
1.                                      5122560    -9 .00512256000000000000000000000000000000000000000000
2.                                 190722470400   -15 .00019072247040000000000000000000000000000000000000
3.                             7574824857600000   -21 .00000757482485760000000000000000000000000000000000
4.                        312546150372456000000   -27 .00000031254615037245600000000000000000000000000000
5.                   13207874703225491420651520   -33 .00000001320787470322549142065152000000000000000000
6.               567273919793089083292259942400   -39 .00000000056727391979308908329225994240000000000000
7.          24650600248172987140112763715584000   -45 .00000000002465060024817298714011276371558400000000
8.     1080657854354639453670407474439566400000   -51 .00000000000108065785435463945367040747443956640000
9. 47701779391594966287470570490839978880000000   -57 .00000000000004770177939159496628747057049083997888

3.1415926535897932384626433832795028841971693993751058209749445923078\
164

Erlang

This version uses integer math only (does not resort to a rational number package) Since the denominator is always a power of 10, it's possible to just keep track of the log of the denominator and scale the numerator accordingly; to keep track of the accuracy we get the order of magnitude of the difference between terms by subtracting the log of the numerator from the log of the denominator, so again, no rational arithmetic is needed.

However, Erlang does not have much in the way of calculating with large integers beyond basic arithmetic, so this version implements integer powers, logs, square roots, as well as the factorial function. <lang Erlang> -mode(compile).

% Integer math routines: factorial, power, square root, integer logarithm. % fac(N) -> fac(N, 1). fac(N, A) when N < 2 -> A; fac(N, A) -> fac(N - 1, N*A).


pow(_, N) when N < 0 -> pow_domain_error; pow(2, N) -> 1 bsl N; pow(A, N) -> ipow(A, N).

ipow(_, 0) -> 1; ipow(A, 1) -> A; ipow(A, 2) -> A*A; ipow(A, N) ->

   case N band 1 of
       0 -> X = ipow(A, N bsr 1), X*X;
       1 -> A * ipow(A, N - 1)
   end.

% integer logarithm, based on Zeckendorf representations of integers. % https://www.keithschwarz.com/interesting/code/?dir=zeckendorf-logarithm % we need this, since the exponents get larger than IEEE-754 double can handle.

lognext({A, B, S, T}) -> {B, A+B, T, S*T}. logprev({A, B, S, T}) -> {B-A, A, T div S, S}.

ilog(A, B) when (A =< 0) or (B < 2) -> ilog_domain_error; ilog(A, B) ->

   UBound = bracket(A, {0, 1, 1, B}),
   backlog(A, UBound, 0).

bracket(A, State = {_, _, _, T}) when T > A -> State; bracket(A, State) -> bracket(A, lognext(State)).

backlog(_, {0, _, 1, _}, Log) -> Log; backlog(N, State = {A, _, S, _}, Log) when S =< N ->

   backlog(N div S, logprev(State), Log + A);

backlog(N, State, Log) -> backlog(N, logprev(State), Log).


isqrt(N) when N < 0 -> isqrt_domain_error; isqrt(N) ->

   X0 = pow(2, ilog(N, 2) div 2),
   iterate(N, newton(X0, N), N).

iterate(A, B, _) when A =< B -> A; iterate(_, B, N) -> iterate(B, newton(B, N), N).

newton(X, N) -> (X + N div X) div 2.


% With this out of the way, we can get down to some serious calculation. % term(N) -> {  % returns numerator and log10 of the denominator.

   (fac(6*N)*(N*(532*N + 126) + 9) bsl 5) div (3*pow(fac(N), 6)),
   6*N + 3
   }.

neg_term({N, D}) -> {-N, D}. abs_term({N, D}) -> {abs(N), D}.

add_term(T1 = {_, D1}, T2 = {_, D2}) when D1 > D2 -> add_term(T2, T1); add_term({N1, D1}, {N2, D2}) ->

   Scale = pow(10, D2 - D1),
   {N1*Scale + N2, D2}.

calculate(Prec) -> calculate(Prec, {0, 0}, 0). calculate(Prec, T0, K) ->

   T1 = add_term(T0, term(K)),
   {N, D} = abs_term(add_term(neg_term(T1), T0)),
   Accuracy = D - ilog(N, 10),
   if
       Accuracy < Prec -> calculate(Prec, T1, K + 1);
       true -> T1
   end.

get_pi(Prec) ->

   {N0, D0} = calculate(Prec),
   % from the term, t = n0/10^d0, calculate 1/√t
   % if the denominator is an odd power of 10, add 1 to the denominator and multiply the numerator by 10.
   {N, D} = case D0 band 1 of
       0 -> {N0, D0};
       1 -> {10*N0, D0 + 1}
   end,
   [Three|Rest] = lists:sublist(
           integer_to_list(pow(10, D) div isqrt(N)), Prec),
   [Three, $. | Rest].

show_term({A, Decimals}) ->

   Str = integer_to_list(A),
   [$0, $.] ++ lists:duplicate(Decimals - length(Str), $0) ++ Str.

main(_) ->

   Terms = [term(N) || N <- lists:seq(0, 9)],
   io:format("The first 10 terms as scaled decimals are:~n"),
   [io:format("    ~s~n", [show_term(T)]) || T <- Terms],
   io:format("~nThe sum of these terms (pi^-2) is ~s~n",
               [show_term(lists:foldl(fun add_term/2, {0, 0}, Terms))]),
   Pi70 = get_pi(71),
   io:format("~npi to 70 decimal places:~n"),
   io:format("~s~n", [Pi70]).

</lang>

Output:
The first 10 terms as scaled decimals are:
    0.096
    0.005122560
    0.000190722470400
    0.000007574824857600000
    0.000000312546150372456000000
    0.000000013207874703225491420651520
    0.000000000567273919793089083292259942400
    0.000000000024650600248172987140112763715584000
    0.000000000001080657854354639453670407474439566400000
    0.000000000000047701779391594966287470570490839978880000000

The sum of these terms (pi^-2) is 0.101321183642335555356499725503850584160514406378880000000

pi to 70 decimal places:
3.1415926535897932384626433832795028841971693993751058209749445923078164

F#

This task uses Isqrt_(integer_square_root)_of_X#F.23 <lang fsharp> // Almkvist-Giullera formula for pi. Nigel Galloway: August 17th., 2021 let factorial(n:bigint)=MathNet.Numerics.SpecialFunctions.Factorial n let fN g=(532I*g*g+126I*g+9I)*(factorial(6I*g))/(3I*(factorial g)**6) [0..9]|>Seq.iter(bigint>>fN>>(*)32I>>printfn "%A\n") let _,n=Seq.unfold(fun(n,g)->let n=n*(10I**6)+fN g in Some(Isqrt((10I**(145+6*(int g)))/(32I*n)),(n,g+1I)))(0I,0I)|>Seq.pairwise|>Seq.find(fun(n,g)->n=g) printfn $"""pi to 70 decimal places is %s{(n.ToString()).Insert(1,".")}""" </lang>

Output:
96
5122560
190722470400
7574824857600000
312546150372456000000
13207874703225491420651520
567273919793089083292259942400
24650600248172987140112763715584000
1080657854354639453670407474439566400000
47701779391594966287470570490839978880000000

pi to 70 decimal places is 3.14159265358979323846264338327950288419716939937510582097494459230781640

Factor

Works with: Factor version 0.99 2020-08-14

<lang factor>USING: continuations formatting io kernel locals math math.factorials math.functions sequences ;

integer-term ( n -- m )
   32 6 n * factorial * 532 n sq * 126 n * + 9 + *
   n factorial 6 ^ 3 * / ;
exponent-term ( n -- m ) 6 * 3 + neg ;
nth-term ( n -- x )
   [ integer-term ] [ exponent-term 10^ * ] bi ;

! Factor doesn't have an arbitrary-precision square root afaik, ! so make one using Heron's method.

sqrt-approx ( r x -- r' x ) [ over / + 2 / ] keep ;
almkvist-guillera ( precision -- x )
   0 0 :> ( summed! next-add! )
   [
       100,000,000 <iota> [| n |
           summed n nth-term + next-add!
           next-add summed - abs precision neg 10^ <
           [ return ] when
           next-add summed!
       ] each
   ] with-return
   next-add ;

CONSTANT: 1/pi 113/355  ! Use as initial guess for square root approximation

pi ( -- )
   1/pi 70 almkvist-guillera 5 [ sqrt-approx ] times
   drop recip "%.70f\n" printf ;

! Task "N Integer Portion Pow Nth Term (33 dp)" print 89 CHAR: - <repetition> print 10 [

   dup [ integer-term ] [ exponent-term ] [ nth-term ] tri
   "%d  %44d  %3d  %.33f\n" printf

] each-integer nl "Pi to 70 decimal places:" print pi</lang>

Output:
N                               Integer Portion  Pow  Nth Term (33 dp)
-----------------------------------------------------------------------------------------
0                                            96   -3  0.096000000000000000000000000000000
1                                       5122560   -9  0.005122560000000000000000000000000
2                                  190722470400  -15  0.000190722470400000000000000000000
3                              7574824857600000  -21  0.000007574824857600000000000000000
4                         312546150372456000000  -27  0.000000312546150372456000000000000
5                    13207874703225491420651520  -33  0.000000013207874703225491420651520
6                567273919793089083292259942400  -39  0.000000000567273919793089083292260
7           24650600248172987140112763715584000  -45  0.000000000024650600248172987140113
8      1080657854354639453670407474439566400000  -51  0.000000000001080657854354639453670
9  47701779391594966287470570490839978880000000  -57  0.000000000000047701779391594966287

Pi to 70 decimal places:
3.1415926535897932384626433832795028841971693993751058209749445923078164

Go

Translation of: Wren

<lang go>package main

import (

   "fmt"
   "math/big"
   "strings"

)

func factorial(n int64) *big.Int {

   var z big.Int
   return z.MulRange(1, n)

}

var one = big.NewInt(1) var three = big.NewInt(3) var six = big.NewInt(6) var ten = big.NewInt(10) var seventy = big.NewInt(70)

func almkvistGiullera(n int64, print bool) *big.Rat {

   t1 := big.NewInt(32)
   t1.Mul(factorial(6*n), t1)
   t2 := big.NewInt(532*n*n + 126*n + 9)
   t3 := new(big.Int)
   t3.Exp(factorial(n), six, nil)
   t3.Mul(t3, three)
   ip := new(big.Int)
   ip.Mul(t1, t2)
   ip.Quo(ip, t3)
   pw := 6*n + 3
   t1.SetInt64(pw)
   tm := new(big.Rat).SetFrac(ip, t1.Exp(ten, t1, nil))
   if print {
       fmt.Printf("%d  %44d  %3d  %-35s\n", n, ip, -pw, tm.FloatString(33))
   }
   return tm

}

func main() {

   fmt.Println("N                               Integer Portion  Pow  Nth Term (33 dp)")
   fmt.Println(strings.Repeat("-", 89))
   for n := int64(0); n < 10; n++ {
       almkvistGiullera(n, true)
   }
   sum := new(big.Rat)
   prev := new(big.Rat)
   pow70 := new(big.Int).Exp(ten, seventy, nil)
   prec := new(big.Rat).SetFrac(one, pow70)
   n := int64(0)
   for {
       term := almkvistGiullera(n, false)
       sum.Add(sum, term)
       z := new(big.Rat).Sub(sum, prev)
       z.Abs(z)
       if z.Cmp(prec) < 0 {
           break
       }
       prev.Set(sum)
       n++
   }
   sum.Inv(sum)
   pi := new(big.Float).SetPrec(256).SetRat(sum)
   pi.Sqrt(pi)
   fmt.Println("\nPi to 70 decimal places is:")
   fmt.Println(pi.Text('f', 70))

}</lang>

Output:
N                               Integer Portion  Pow  Nth Term (33 dp)
-----------------------------------------------------------------------------------------
0                                            96   -3  0.096000000000000000000000000000000
1                                       5122560   -9  0.005122560000000000000000000000000
2                                  190722470400  -15  0.000190722470400000000000000000000
3                              7574824857600000  -21  0.000007574824857600000000000000000
4                         312546150372456000000  -27  0.000000312546150372456000000000000
5                    13207874703225491420651520  -33  0.000000013207874703225491420651520
6                567273919793089083292259942400  -39  0.000000000567273919793089083292260
7           24650600248172987140112763715584000  -45  0.000000000024650600248172987140113
8      1080657854354639453670407474439566400000  -51  0.000000000001080657854354639453670
9  47701779391594966287470570490839978880000000  -57  0.000000000000047701779391594966287

Pi to 70 decimal places is:
3.1415926535897932384626433832795028841971693993751058209749445923078164

Haskell

Library: numbers
Translation of: Common Lisp

<lang haskell>import Control.Monad import Data.Number.CReal import GHC.Integer import Text.Printf

iterations = 52 main = do

 printf "N. %44s %4s %s\n" 
         "Integral part of Nth term" "×10^" "=Actual value of Nth term"
 forM_ [0..9] $ \n ->
   printf "%d. %44d %4d %s\n" n
                              (almkvistGiulleraIntegral n)
                              (tenExponent n)
                              (showCReal 50 (almkvistGiullera n))
 printf "\nPi after %d iterations:\n" iterations
 putStrLn $ showCReal 70 $ almkvistGiulleraPi iterations

-- The integral part of the Nth term in the Almkvist-Giullera series almkvistGiulleraIntegral n =

 let polynomial  = (532 `timesInteger` n `timesInteger` n) `plusInteger` (126 `timesInteger` n) `plusInteger` 9
     numerator   = 32 `timesInteger` (facInteger (6 `timesInteger` n)) `timesInteger` polynomial
     denominator = 3 `timesInteger` (powInteger (facInteger n) 6)
  in numerator `divInteger` denominator

-- The exponent for 10 in the Nth term of the series tenExponent n = 3 `minusInteger` (6 `timesInteger` (1 `plusInteger` n))

-- The Nth term in the series (integral * 10^tenExponent) almkvistGiullera n = fromInteger (almkvistGiulleraIntegral n) / fromInteger (powInteger 10 (abs (tenExponent n)))

-- The sum of the first N terms almkvistGiulleraSum n = sum $ map almkvistGiullera [0 .. n]

-- The approximation of pi from the first N terms almkvistGiulleraPi n = sqrt $ 1 / almkvistGiulleraSum n

-- Utility: factorial for arbitrary-precision integers facInteger n = if n `leInteger` 1 then 1 else n `timesInteger` facInteger (n `minusInteger` 1)

-- Utility: exponentiation for arbitrary-precision integers powInteger 1 _ = 1 powInteger _ 0 = 1 powInteger b 1 = b powInteger b e = b `timesInteger` powInteger b (e `minusInteger` 1) </lang>

Output:
N.                    Integral part of Nth term ×10^ =Actual value of Nth term
0.                                           96   -3 0.096
1.                                      5122560   -9 0.00512256
2.                                 190722470400  -15 0.0001907224704
3.                             7574824857600000  -21 0.0000075748248576
4.                        312546150372456000000  -27 0.000000312546150372456
5.                   13207874703225491420651520  -33 0.00000001320787470322549142065152
6.               567273919793089083292259942400  -39 0.0000000005672739197930890832922599424
7.          24650600248172987140112763715584000  -45 0.000000000024650600248172987140112763715584
8.     1080657854354639453670407474439566400000  -51 0.0000000000010806578543546394536704074744395664
9. 47701779391594966287470570490839978880000000  -57 0.00000000000004770177939159496628747057049083997888

Pi after 52 iterations:
3.1415926535897932384626433832795028841971693993751058209749445923078164

J

This solution just has it hard-coded that 53 iterations is necessary for 70 decimals. It would be possible to write a loop with a test, though in practice it would also be acceptable to just experiment to find the number of iterations.

sqrt is noticeably slow, bringing execution time to over 1 second. I'm not sure if it's because it's coded imperatively using traditional loops vs. J point-free style, or if it's due to the fact that the numbers are very large. I suspect the latter since it only takes 4 iterations of Heron's method to get the square root. <lang J> numerator =: monad define "0

   (3 * (! x: y)^6) %~ 32 * (!6x*y) * (y*(126 + 532*y)) + 9x

)

term =: numerator % 10x ^ 3 + 6&*

echo 'The first 10 numerators are:' echo ,. numerator i.10

echo echo 'The sum of the first 10 terms (pi^-2) is ', 0j15 ": +/ term i.10

heron =: [: -: ] + %

sqrt =: dyad define NB. usage: x0 tolerance sqrt x

                   NB. e.g.: (1, %10^100x) sqrt 2 -> √2 to 100 decimals as a ratio p/q
   x0  =. }: x
   eps =. }. x
   x1  =. y heron x0
   while. (| x1 - x0) > eps do.
       x2 =. y heron x1
       x0 =. x1
       x1 =. x2
   end.
   x1

)

pi70 =. (355r113, %10^70x) sqrt % +/ term i.53 echo echo 'pi to 70 decimals: ', 0j70 ": pi70 exit </lang>

Output:
The first 10 numerators are:
                                          96
                                     5122560
                                190722470400
                            7574824857600000
                       312546150372456000000
                  13207874703225491420651520
              567273919793089083292259942400
         24650600248172987140112763715584000
    1080657854354639453670407474439566400000
47701779391594966287470570490839978880000000

The sum of the first 10 terms (pi^-2) is 0.101321183642336

pi to 70 decimals: 3.1415926535897932384626433832795028841971693993751058209749445923078164

JavaScript

Translation of: Common Lisp
Works with: Node.js version 13+
Library: es-main

to support use of module as main code

<lang javascript>import esMain from 'es-main'; import { BigFloat, set_precision as SetPrecision } from 'bigfloat-esnext';

const Iterations = 52;

export const demo = function() {

 SetPrecision(-75);
 console.log("N." + "Integral part of Nth term".padStart(45) + " ×10^ =Actual value of Nth term");
 for (let i=0; i<10; i++) {
   let line = `${i}. `;
   line += `${integral(i)} `.padStart(45);
   line += `${tenExponent(i)} `.padStart(5);
   line += nthTerm(i);
   console.log(line);
 }
 let pi = approximatePi(Iterations);
 SetPrecision(-70);
 pi = pi.dividedBy(100000).times(100000);
 console.log(`\nPi after ${Iterations} iterations: ${pi}`)

}

export const bigFactorial = n => n <= 1n ? 1n : n * bigFactorial(n-1n);

// the nth integer term export const integral = function(i) {

 let n = BigInt(i);
 const polynomial  = 532n * n * n + 126n * n + 9n;
 const numerator   = 32n * bigFactorial(6n * n) * polynomial;
 const denominator = 3n * bigFactorial(n) ** 6n;
 return numerator / denominator;

}

// the exponent for 10 in the nth term of the series export const tenExponent = n => 3n - 6n * (BigInt(n) + 1n);

// the nth term of the series export const nthTerm = n =>

 new BigFloat(integral(n)).dividedBy(new BigFloat(10n ** -tenExponent(n)))

// the sum of the first n terms export const sumThrough = function(n) {

 let sum = new BigFloat(0);
 for (let i=0; i<=n; ++i) {
   sum = sum.plus(nthTerm(i));
 }
 return sum;

}

// the approximation to pi after n terms export const approximatePi = n =>

  new BigFloat(1).dividedBy(sumThrough(n)).sqrt();

if (esMain(import.meta))

  demo();

</lang>

Output:
N.                    Integral part of Nth term ×10^ =Actual value of Nth term
0.                                           96   -3 0.096
1.                                      5122560   -9 0.00512256
2.                                 190722470400  -15 0.0001907224704
3.                             7574824857600000  -21 0.0000075748248576
4.                        312546150372456000000  -27 0.000000312546150372456
5.                   13207874703225491420651520  -33 0.00000001320787470322549142065152
6.               567273919793089083292259942400  -39 0.0000000005672739197930890832922599424
7.          24650600248172987140112763715584000  -45 0.000000000024650600248172987140112763715584
8.     1080657854354639453670407474439566400000  -51 0.0000000000010806578543546394536704074744395664
9. 47701779391594966287470570490839978880000000  -57 0.00000000000004770177939159496628747057049083997888

Pi after 52 iterations: 3.1415926535897932384626433832795028841971693993751058209749445923078164

jq

Adapted from Wren

Works with gojq, the Go implementation of jq

This entry uses the "rational" module, which can be found at Arithmetic/Rational#jq.

Preliminaries <lang jq># A reminder to include the "rational" module:

  1. include "rational";

def lpad($len): tostring | ($len - length) as $l | (" " * $l)[:$l] + .;

  1. To take advantage of gojq's arbitrary-precision integer arithmetic:

def power($b): . as $in | reduce range(0;$b) as $i (1; . * $in);

def factorial:

   if . < 2 then 1
   else reduce range(2;.+1) as $i (1; .*$i)
   end; </lang>

Almkvist-Giullera Formula <lang jq> def almkvistGiullera(print):

 . as $n
 | ((6*$n) | factorial * 32) as $t1
 | (532*$n*$n + 126*$n + 9) as $t2
 | (($n | factorial | power(6))*3) as $t3
 | ($t1 * $t2 / $t3) as $ip
 | ( 6*$n + 3) as $pw
 | r($ip; 10 | power($pw)) as $tm
 | if print
   then "\($n|lpad(2)) \($ip|lpad(44)) \(-$pw|lpad(3)), \($tm|r_to_decimal(100))"
   else $tm
   end; </lang>

The Tasks <lang jq> def task1:

 "N                               Integer Portion  Pow  Nth Term",
 ("-" * 89),
 (range(0;10) | almkvistGiullera(true)) ;

def task2($precision):

 r(1; 10 | power($precision)) as $p
 | {sum: r(0;1), prev: r(0;1), n:  0 }
 | until(.stop;
   .sum = radd(.sum; .n | almkvistGiullera(false))
   | if rminus(.sum; .prev) | rabs | rlessthan($p)
     then .stop = true
     else .prev = .sum
     | .n += 1
     end)
  | .sum | rinv
  | rsqrt($precision)
  | "\nPi to \($precision) decimal places is:",
   "\(r_to_decimal($precision))" ;

task1, "" task2(70)</lang>

Output:
N                               Integer Portion  Pow  Nth Term
-----------------------------------------------------------------------------------------
 0                                           96  -3, 0.096
 1                                      5122560  -9, 0.00512256
 2                                 190722470400 -15, 0.0001907224704
 3                             7574824857600000 -21, 0.0000075748248576
 4                        312546150372456000000 -27, 0.000000312546150372456
 5                   13207874703225491420651520 -33, 0.00000001320787470322549142065152
 6               567273919793089083292259942400 -39, 0.0000000005672739197930890832922599424
 7          24650600248172987140112763715584000 -45, 0.000000000024650600248172987140112763715584
 8     1080657854354639453670407474439566400000 -51, 0.0000000000010806578543546394536704074744395664
 9 47701779391594966287470570490839978880000000 -57, 0.00000000000004770177939159496628747057049083997888

Pi to 70 decimal places is:
3.1415926535897932384626433832795028841971693993751058209749445923078164

Julia

<lang julia>using Formatting

setprecision(BigFloat, 300)

function integerterm(n)

   p = BigInt(532) * n * n + BigInt(126) * n + 9
   return (p * BigInt(2)^5 * factorial(BigInt(6) * n)) ÷ (3 * factorial(BigInt(n))^6)

end

exponentterm(n) = -(6n + 3)

nthterm(n) = integerterm(n) * big"10.0"^exponentterm(n)

println(" N Integer Term Power of 10 Nth Term") println("-"^90) for n in 0:9

   println(lpad(n, 3), lpad(integerterm(n), 48), lpad(exponentterm(n), 4),
       lpad(format("{1:22.19e}", nthterm(n)), 35))

end

function AlmkvistGuillera(floatprecision)

   summed = nthterm(0)
   for n in 1:10000000
       next = summed + nthterm(n)
       if abs(next - summed) < big"10.0"^(-floatprecision)
           return next
       end
       summed = next
   end

end

println("\nπ to 70 digits is ", format(big"1.0" / sqrt(AlmkvistGuillera(70)), precision=70))

println("Computer π is ", format(π + big"0.0", precision=70))

</lang>

Output:
  N                       Integer Term              Power of 10     Nth Term
------------------------------------------------------------------------------------------
  0                                              96  -3          9.6000000000000000000e-02
  1                                         5122560  -9          5.1225600000000000000e-03
  2                                    190722470400 -15          1.9072247040000000000e-04
  3                                7574824857600000 -21          7.5748248576000000000e-06
  4                           312546150372456000000 -27          3.1254615037245600000e-07
  5                      13207874703225491420651520 -33          1.3207874703225491421e-08
  6                  567273919793089083292259942400 -39          5.6727391979308908329e-10
  7             24650600248172987140112763715584000 -45          2.4650600248172987140e-11
  8        1080657854354639453670407474439566400000 -51          1.0806578543546394537e-12
  9    47701779391594966287470570490839978880000000 -57          4.7701779391594966287e-14

π to 70 digits is 3.1415926535897932384626433832795028841971693993751058209749445923078164
Computer π is     3.1415926535897932384626433832795028841971693993751058209749445923078164

Mathematica/Wolfram Language

<lang Mathematica>ClearAll[numerator, denominator] numerator[n_] := (2^5) ((6 n)!) (532 n^2 + 126 n + 9)/(3 (n!)^6) denominator[n_] := 10^(6 n + 3) numerator /@ Range[0, 9] val = 1/Sqrt[Total[numerator[#]/denominator[#] & /@ Range[0, 100]]]; N[val, 70]</lang>

Output:
{96,5122560,190722470400,7574824857600000,312546150372456000000,13207874703225491420651520,567273919793089083292259942400,24650600248172987140112763715584000,1080657854354639453670407474439566400000,47701779391594966287470570490839978880000000}
3.141592653589793238462643383279502884197169399375105820974944592307816

Nim

Library: nim-decimal

Derived from Wren version with some simplifications. <lang Nim>import strformat, strutils import decimal

proc fact(n: int): DecimalType =

 result = newDecimal(1)
 if n < 2: return
 for i in 2..n:
   result *= i

proc almkvistGiullera(n: int): DecimalType =

 ## Return the integer portion of the nth term of Almkvist-Giullera sequence.
 let t1 = fact(6 * n) * 32
 let t2 = 532 * n * n + 126 * n + 9
 let t3 = fact(n) ^ 6 * 3
 result = t1 * t2 / t3

let One = newDecimal(1)

setPrec(78) echo "N Integer portion" echo repeat('-', 47) for n in 0..9:

 echo &"{n}  {almkvistGiullera(n):>44}"

echo()

echo "Pi to 70 decimal places:" var

 sum = newDecimal(0)
 prev = newDecimal(0)
 prec = One.scaleb(newDecimal(-70))
 n = 0

while true:

 sum += almkvistGiullera(n) / One.scaleb(newDecimal(6 * n + 3))
 if abs(sum - prev) < prec: break
 prev = sum.clone
 inc n

let pi = 1 / sqrt(sum) echo ($pi)[0..71]</lang>

Output:
N                               Integer portion
-----------------------------------------------
0                                            96
1                                       5122560
2                                  190722470400
3                              7574824857600000
4                         312546150372456000000
5                    13207874703225491420651520
6                567273919793089083292259942400
7           24650600248172987140112763715584000
8      1080657854354639453670407474439566400000
9  47701779391594966287470570490839978880000000

Pi to 70 decimal places:
3.1415926535897932384626433832795028841971693993751058209749445923078164

Perl

Translation of: Raku

<lang perl>use strict; use warnings; use feature qw(say); use Math::AnyNum qw(:overload factorial);

sub almkvist_giullera_integral {

   my($n) = @_;
   (32 * (14*$n * (38*$n + 9) + 9) * factorial(6*$n)) / (3*factorial($n)**6);

}

sub almkvist_giullera {

   my($n) = @_;
   almkvist_giullera_integral($n) / (10**(6*$n + 3));

}

sub almkvist_giullera_pi {

   my ($prec) = @_;
   local $Math::AnyNum::PREC = 4*($prec+1);
   my $sum = 0;
   my $target = ;
   for (my $n = 0; ; ++$n) {
       $sum += almkvist_giullera($n);
       my $curr = ($sum**-.5)->as_dec;
       return $target if ($curr eq $target);
       $target = $curr;
   }

}

say 'First 10 integer portions: '; say "$_ " . almkvist_giullera_integral($_) for 0..9;

my $precision = 70;

printf("π to %s decimal places is:\n%s\n",

   $precision, almkvist_giullera_pi($precision));</lang>
Output:
First 10 integer portions:
0  96
1  5122560
2  190722470400
3  7574824857600000
4  312546150372456000000
5  13207874703225491420651520
6  567273919793089083292259942400
7  24650600248172987140112763715584000
8  1080657854354639453670407474439566400000
9  47701779391594966287470570490839978880000000
π to 70 decimal places is:
3.1415926535897932384626433832795028841971693993751058209749445923078164

Phix

with javascript_semantics
requires("1.0.0") 
include mpfr.e
mpfr_set_default_precision(-70)
 
function almkvistGiullera(integer n, bool bPrint)
    mpz {t1,t2,ip} = mpz_inits(3)
    mpz_fac_ui(t1,6*n) 
    mpz_mul_si(t1,t1,32)                -- t1:=2^5*(6n)!
    mpz_fac_ui(t2,n)
    mpz_pow_ui(t2,t2,6)
    mpz_mul_si(t2,t2,3)                 -- t2:=3*(n!)^6
    mpz_mul_si(ip,t1,532*n*n+126*n+9)   -- ip:=t1*(532n^2+126n+9)
    mpz_fdiv_q(ip,ip,t2)                -- ip:=ip/t2
    integer pw := 6*n+3
    mpz_ui_pow_ui(t1,10,pw)             -- t1 := 10^(6n+3)
    mpq tm = mpq_init_set_z(ip,t1)      -- tm := rat(ip/t1)
    if bPrint then
        string ips = mpz_get_str(ip),
               tms = mpfr_get_fixed(mpfr_init_set_q(tm),50)
        tms = trim_tail(tms,"0")
        printf(1,"%d  %44s  %3d  %s\n", {n, ips, -pw, tms})
    end if
    return tm
end function
 
constant hdr = "N --------------- Integer portion -------------  Pow  ----------------- Nth term (50 dp) -----------------"
printf(1,"%s\n%s\n",{hdr,repeat('-',length(hdr))})
for n=0 to 9 do
    {} = almkvistGiullera(n, true)
end for
 
mpq {res,prev,z} = mpq_inits(3),
    prec = mpq_init_set_str(sprintf("1/1%s",repeat('0',70)))
integer n = 0
while true do
    mpq term := almkvistGiullera(n, false)
    mpq_add(res,res,term)
    mpq_sub(z,res,prev)
    mpq_abs(z,z)
    if mpq_cmp(z,prec) < 0 then exit end if
    mpq_set(prev,res)
    n += 1
end while
mpq_inv(res,res)
mpfr pi = mpfr_init_set_q(res)
mpfr_sqrt(pi,pi)
printf(1,"\nCalculation of pi took %d iterations using the Almkvist-Giullera formula.\n\n",n)
printf(1,"Pi to 70 d.p.: %s\n",mpfr_get_fixed(pi,70))
mpfr_const_pi(pi)
printf(1,"Pi (builtin) : %s\n",mpfr_get_fixed(pi,70))
Output:
N --------------- Integer portion -------------  Pow  ----------------- Nth term (50 dp) -----------------
----------------------------------------------------------------------------------------------------------
0                                            96   -3  0.096
1                                       5122560   -9  0.00512256
2                                  190722470400  -15  0.0001907224704
3                              7574824857600000  -21  0.0000075748248576
4                         312546150372456000000  -27  0.000000312546150372456
5                    13207874703225491420651520  -33  0.00000001320787470322549142065152
6                567273919793089083292259942400  -39  0.0000000005672739197930890832922599424
7           24650600248172987140112763715584000  -45  0.000000000024650600248172987140112763715584
8      1080657854354639453670407474439566400000  -51  0.0000000000010806578543546394536704074744395664
9  47701779391594966287470570490839978880000000  -57  0.00000000000004770177939159496628747057049083997888

Calculation of pi took 52 iterations using the Almkvist-Giullera formula.

Pi to 70 d.p.: 3.1415926535897932384626433832795028841971693993751058209749445923078164
Pi (builtin) : 3.1415926535897932384626433832795028841971693993751058209749445923078164

Python

<lang python>import mpmath as mp

with mp.workdps(72):

   def integer_term(n):
       p = 532 * n * n + 126 * n + 9
       return (p * 2**5 * mp.factorial(6 * n)) / (3 * mp.factorial(n)**6)
   def exponent_term(n):
       return -(mp.mpf("6.0") * n + 3)
   def nthterm(n):
       return integer_term(n) * mp.mpf("10.0")**exponent_term(n)


   for n in range(10):
       print("Term ", n, '  ', int(integer_term(n)))


   def almkvist_guillera(floatprecision):
       summed, nextadd = mp.mpf('0.0'), mp.mpf('0.0')
       for n in range(100000000):
           nextadd = summed + nthterm(n)
           if abs(nextadd - summed) < 10.0**(-floatprecision):
               break
           summed = nextadd
       return nextadd


   print('\nπ to 70 digits is ', end=)
   mp.nprint(mp.mpf(1.0 / mp.sqrt(almkvist_guillera(70))), 71)
   print('mpmath π is       ', end=)
   mp.nprint(mp.pi, 71)

</lang>

Output:
Term  0    96
Term  1    5122560
Term  2    190722470400
Term  3    7574824857600000
Term  4    312546150372456000000
Term  5    13207874703225491420651520
Term  6    567273919793089083292259942400
Term  7    24650600248172987140112763715584000
Term  8    1080657854354639453670407474439566400000
Term  9    47701779391594966287470570490839978880000000

π to 70 digits is 3.1415926535897932384626433832795028841971693993751058209749445923078164
mpmath π is       3.1415926535897932384626433832795028841971693993751058209749445923078164

Quackery

<lang Quackery> [ $ "bigrat.qky" loadfile ] now!

 [ 1 swap times [ i^ 1+ * ] ] is !       ( n --> n   )
 [ dup dup 2 ** 532 *
   over 126 * + 9 +
   swap 6 * ! * 32 *
   swap ! 6 ** 3 * / ]        is intterm ( n --> n   )
 [ dup intterm 
   10 rot 6 * 3 + ** 
   reduce ]                   is vterm   ( n --> n/d )
 10 times [ i^ intterm echo cr ] cr
 
 0 n->v 
 53 times [ i^ vterm v+ ]
 1/v 70 vsqrt drop 
 70 point$ echo$ cr</lang>
Output:
96
5122560
190722470400
7574824857600000
312546150372456000000
13207874703225491420651520
567273919793089083292259942400
24650600248172987140112763715584000
1080657854354639453670407474439566400000
47701779391594966287470570490839978880000000

3.1415926535897932384626433832795028841971693993751058209749445923078164

Raku

<lang perl6># 20201013 Raku programming solution

use BigRoot; use Rat::Precise; use experimental :cached;

BigRoot.precision = 75 ; my $Precision = 70 ; my $AGcache = 0 ;

sub postfix:<!>(Int $n --> Int) is cached { [*] 1 .. $n }

sub Integral(Int $n --> Int) is cached {

  (2⁵*(6*$n)! * (532*$n² + 126*$n + 9)) div (3*($n!)⁶)

}

sub A-G(Int $n --> FatRat) is cached { # Almkvist-Giullera

  Integral($n).FatRat / (10**(6*$n + 3)).FatRat

}

sub Pi(Int $n --> Str) {

  (1/(BigRoot.newton's-sqrt: $AGcache += A-G $n)).precise($Precision)

}

say "First 10 integer portions : "; say $_, "\t", Integral $_ for ^10;

my $target = Pi my $Nth = 0;

loop { $target eq ( my $next = Pi ++$Nth ) ?? ( last ) !! $target = $next }

say "π to $Precision decimal places is :\n$target"</lang>

Output:
First 10 integer portions :
0       96
1       5122560
2       190722470400
3       7574824857600000
4       312546150372456000000
5       13207874703225491420651520
6       567273919793089083292259942400
7       24650600248172987140112763715584000
8       1080657854354639453670407474439566400000
9       47701779391594966287470570490839978880000000
π to 70 decimal places is :
3.1415926535897932384626433832795028841971693993751058209749445923078164

REXX

<lang rexx>/*REXX program uses the Almkvist─Giullera formula for 1 / (pi**2) [or pi ** -2]. */ numeric digits length( pi() ) + length(.); w= 102 say $( , 3) $( , w%2) $('power', 5) $( , w) say $('N', 3) $('integer term', w%2) $('of 10', 5) $('Nth term', w) say $( , 3, "─") $( , w%2, "─") $( , 5, "─") $( , w, "─")

                                 s= 0           /*initialize   S   (the sum)  to zero. */
    do n=0  until old=s;    old= s              /*use the "older" value of  S  for OLD.*/
    a= 2**5  *  !(6*n)  *  (532 * n**2  +  126*n  +  9)  /  (3 * !(n)**6)
    z= 10 ** (- (6*n + 3) )
    s= s     +   a * z
    if n>10  then do;  do 3*(n==11);  say ' .';  end;  iterate;  end
    say $(n, 3) right(a, w%2)  $(powX(z), 5)  right( lowE( format(a*z, 1, w-6, 2, 0)), w)
    end   /*n*/

say say 'The calculation of pi took ' n " iterations with " digits() ,

   " decimal digits precision using"   subword( sourceLine(1), 4, 3).

say numeric digits length( pi() ) - length(.); d= digits() - length(.); @= ' ↓↓↓ ' say center(@ 'calculated pi to ' d " fractional decimal digits (below) is "@, d+4, '─') say ' 'sqrt(1/s); say say ' 'pi(); @= ' ↑↑↑ ' say center(@ 'the true pi to ' d " fractional decimal digits (above) is" @, d+4, '─') exit 0 /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ $: procedure; parse arg text,width,fill; return center(text, width, left(fill, 1) ) !: procedure; parse arg x; !=1;; do j=2 to x;  != !*j; end; return ! lowE: procedure; parse arg x; return translate(x, 'e', "E") powX: procedure; parse arg p; return right( format( p, 1, 3, 2, 0), 3) + 0 /*──────────────────────────────────────────────────────────────────────────────────────*/ pi: pi=3.141592653589793238462643383279502884197169399375105820974944592307816406286208,

     ||9986280348253421170679821480865132823066470938446095505822317253594081284811174503
     return pi

/*──────────────────────────────────────────────────────────────────────────────────────*/ sqrt: procedure; parse arg x; if x=0 then return 0; d=digits(); numeric digits; h=d+6

     m.=9; numeric form; parse value format(x,2,1,,0) 'E0' with g 'E' _ .; g=g*.5'e'_ % 2
       do j=0  while h>9;        m.j= h;                 h= h % 2  +  1;       end  /*j*/
       do k=j+5  to 0  by -1;    numeric digits m.k;     g= (g + x/g) * .5;    end  /*k*/
     numeric digits d;           return g/1</lang>
output   when using the internal default input:

(Shown at two─thirds size.)

                                                        power
 N                     integer term                     of 10                                                Nth term
─── ─────────────────────────────────────────────────── ───── ──────────────────────────────────────────────────────────────────────────────────────────────────────
 0                                                   96  -3   9.600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000e-02
 1                                              5122560  -9   5.122560000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000e-03
 2                                         190722470400  -15  1.907224704000000000000000000000000000000000000000000000000000000000000000000000000000000000000000e-04
 3                                     7574824857600000  -21  7.574824857600000000000000000000000000000000000000000000000000000000000000000000000000000000000000e-06
 4                                312546150372456000000  -27  3.125461503724560000000000000000000000000000000000000000000000000000000000000000000000000000000000e-07
 5                           13207874703225491420651520  -33  1.320787470322549142065152000000000000000000000000000000000000000000000000000000000000000000000000e-08
 6                       567273919793089083292259942400  -39  5.672739197930890832922599424000000000000000000000000000000000000000000000000000000000000000000000e-10
 7                  24650600248172987140112763715584000  -45  2.465060024817298714011276371558400000000000000000000000000000000000000000000000000000000000000000e-11
 8             1080657854354639453670407474439566400000  -51  1.080657854354639453670407474439566400000000000000000000000000000000000000000000000000000000000000e-12
 9         47701779391594966287470570490839978880000000  -57  4.770177939159496628747057049083997888000000000000000000000000000000000000000000000000000000000000e-14
10    2117262852373157207626265529989139651218848358400  -63  2.117262852373157207626265529989139651218848358400000000000000000000000000000000000000000000000000e-15
 .
 .
 .

The calculation of pi took  122  iterations with  163  decimal digits precision using the Almkvist─Giullera formula.

────────────────────────────────────────────── ↓↓↓  calculated pi to  160  fractional decimal digits (below) is  ↓↓↓ ───────────────────────────────────────────────
 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174503

 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174503
────────────────────────────────────────────── ↑↑↑  the  true  pi to  160  fractional decimal digits (above) is  ↑↑↑ ───────────────────────────────────────────────

Sidef

<lang ruby>func almkvist_giullera(n) {

   (32 * (14*n * (38*n + 9) + 9) * (6*n)!) / (3 * n!**6)

}

func almkvist_giullera_pi(prec = 70) {

   local Num!PREC = (4*(prec+1)).numify
   var sum = 0
   var target = -1
   for n in (0..Inf) {
       sum += (almkvist_giullera(n) / (10**(6*n + 3)))
       var curr = (sum**-.5).as_dec
       return target if (target == curr)
       target = curr
   }

}

say 'First 10 integer portions: '

10.of {|n|

   say "#{n} #{almkvist_giullera(n)}"

}

with(70) {|n|

   say "π to #{n} decimal places is:"
   say almkvist_giullera_pi(n)

}</lang>

Output:
First 10 integer portions: 
0 96
1 5122560
2 190722470400
3 7574824857600000
4 312546150372456000000
5 13207874703225491420651520
6 567273919793089083292259942400
7 24650600248172987140112763715584000
8 1080657854354639453670407474439566400000
9 47701779391594966287470570490839978880000000
π to 70 decimal places is:
3.1415926535897932384626433832795028841971693993751058209749445923078164

Visual Basic .NET

Translation of: C#

<lang vbnet>Imports System, BI = System.Numerics.BigInteger, System.Console

Module Module1

   Function isqrt(ByVal x As BI) As BI
       Dim t As BI, q As BI = 1, r As BI = 0
       While q <= x : q <<= 2 : End While
       While q > 1 : q >>= 2 : t = x - r - q : r >>= 1
           If t >= 0 Then x = t : r += q
       End While : Return r
   End Function
   Function dump(ByVal digs As Integer, ByVal Optional show As Boolean = False) As String
       digs += 1
       Dim z As Integer, gb As Integer = 1, dg As Integer = digs + gb
       Dim te As BI, t1 As BI = 1, t2 As BI = 9, t3 As BI = 1, su As BI = 0, t As BI = BI.Pow(10, If(dg <= 60, 0, dg - 60)), d As BI = -1, fn As BI = 1
       For n As BI = 0 To dg - 1
           If n > 0 Then t3 = t3 * BI.Pow(n, 6)
           te = t1 * t2 / t3 : z = dg - 1 - CInt(n) * 6
           If z > 0 Then te = te * BI.Pow(10, z) Else te = te / BI.Pow(10, -z)
           If show AndAlso n < 10 Then WriteLine("{0,2} {1,62}", n, te * 32 / 3 / t)
           su += te : If te < 10 Then
               digs -= 1
               If show Then WriteLine(vbLf & "{0} iterations required for {1} digits " & _
                   "after the decimal point." & vbLf, n, digs)
               Exit For
           End If
           For j As BI = n * 6 + 1 To n * 6 + 6
               t1 = t1 * j : Next
           d += 2 : t2 += 126 + 532 * d
       Next
       Dim s As String = String.Format("{0}", isqrt(BI.Pow(10, dg * 2 + 3) _
           / su / 32 * 3 * BI.Pow(CType(10, BI), dg + 5)))
       Return s(0) & "." & s.Substring(1, digs)
   End Function
   Sub Main(ByVal args As String())
       WriteLine(dump(70, true))
   End Sub

End Module</lang>

Output:
 0  9600000000000000000000000000000000000000000000000000000000000
 1   512256000000000000000000000000000000000000000000000000000000
 2    19072247040000000000000000000000000000000000000000000000000
 3      757482485760000000000000000000000000000000000000000000000
 4       31254615037245600000000000000000000000000000000000000000
 5        1320787470322549142065152000000000000000000000000000000
 6          56727391979308908329225994240000000000000000000000000
 7           2465060024817298714011276371558400000000000000000000
 8            108065785435463945367040747443956640000000000000000
 9              4770177939159496628747057049083997888000000000000

53 iterations required for 70 digits after the decimal point.

3.1415926535897932384626433832795028841971693993751058209749445923078164

Wren

Library: Wren-big
Library: Wren-fmt

<lang ecmascript>import "/big" for BigInt, BigRat import "/fmt" for Fmt

var factorial = Fn.new { |n|

   if (n < 2) return BigInt.one
   var fact = BigInt.one
   for (i in 2..n) fact = fact * i
   return fact

}

var almkvistGiullera = Fn.new { |n, print|

   var t1 = factorial.call(6*n) * 32
   var t2 = 532*n*n + 126*n + 9
   var t3 = factorial.call(n).pow(6)*3
   var ip = t1 * t2 / t3
   var pw = 6*n + 3
   var tm = BigRat.new(ip, BigInt.ten.pow(pw))
   if (print) {
       Fmt.print("$d  $44i  $3d  $-35s", n, ip, -pw, tm.toDecimal(33))
   } else {
       return tm
   }

}

System.print("N Integer Portion Pow Nth Term (33 dp)") System.print("-" * 89) for (n in 0..9) {

   almkvistGiullera.call(n, true)

}

var sum = BigRat.zero var prev = BigRat.zero var prec = BigRat.new(BigInt.one, BigInt.ten.pow(70)) var n = 0 while(true) {

   var term = almkvistGiullera.call(n, false)
   sum = sum + term
   if ((sum-prev).abs < prec) break
   prev = sum
   n = n + 1

} var pi = BigRat.one/sum.sqrt(70) System.print("\nPi to 70 decimal places is:") System.print(pi.toDecimal(70))</lang>

Output:
N                               Integer Portion  Pow  Nth Term (33 dp)
-----------------------------------------------------------------------------------------
0                                            96   -3  0.096                              
1                                       5122560   -9  0.00512256                         
2                                  190722470400  -15  0.0001907224704                    
3                              7574824857600000  -21  0.0000075748248576                 
4                         312546150372456000000  -27  0.000000312546150372456            
5                    13207874703225491420651520  -33  0.00000001320787470322549142065152 
6                567273919793089083292259942400  -39  0.000000000567273919793089083292260
7           24650600248172987140112763715584000  -45  0.000000000024650600248172987140113
8      1080657854354639453670407474439566400000  -51  0.000000000001080657854354639453670
9  47701779391594966287470570490839978880000000  -57  0.000000000000047701779391594966287

Pi to 70 decimal places is:
3.1415926535897932384626433832795028841971693993751058209749445923078164