Sequence of primorial primes: Difference between revisions

=={{header|Phix}}==

Horribly slow...

Uses primes[] and add_block() from [[Extensible_prime_generator#Phix|Extensible_prime_generator]]

and Miller_Rabin() from [[Miller–Rabin_primality_test#Phix|Miller–Rabin_primality_test]]

<lang Phix>while length(primes)<100 do add_block() end while

integer primorial = 1

constant integer base = iff(machine_bits()=32?1000:1000000000)

constant integer digits_per = length(sprint(base-1))

constant string dpfmt = sprintf("%%0%dd",digits_per)

-- start at the back, number grows to the right (like little endian)

sequence bigint = {primorial}

atom result

procedure bi_mul(integer pn)

integer carry = 0

for i=1 to length(bigint) do

result = pn*bigint[i]+carry

carry = floor(result/base)

bigint[i] = result-carry*base

end for

while carry <> 0 do

result = carry

carry = floor(carry/base)

bigint &= result-carry*base

end while

end procedure

procedure bi_add(integer carry)

for i=1 to length(bigint) do

result = bigint[i]+carry

carry = floor(result/base)

bigint[i] = result-carry*base

if carry=0 then return end if

end for

if carry!=0 then

if carry<0

or carry!=floor(carry/base) then

?9/0 -- sanity check

end if

bigint &= carry

end if

end procedure

integer found = 0

for n=1 to 100 do

bi_mul(primes[n])

sequence save_bigint = bigint

for pm1=-1 to 2 by 3 do -- (ie n-1 then n+1)

bi_add(pm1)

string bis = sprint(bigint[$])

for i=length(bigint)-1 to 1 by -1 do

bis &= sprintf(dpfmt,bigint[i])

end for

printf(1,"working [%d]...\r",{n})

if Miller_Rabin(bis,1)=PROBABLY_PRIME then

if length(bis)>20 then

bis = sprintf("[big (%d digits)]",length(bis))

end if

printf(1,"%d (%s) is a primorial prime\n",{n,bis})

found += 1

exit

end if

end for

bigint = save_bigint

if found>=12 then exit end if

end for</lang>

{{out}}

<pre>

1 (3) is a primorial prime

2 (5) is a primorial prime

3 (29) is a primorial prime

4 (211) is a primorial prime

5 (2309) is a primorial prime

6 (30029) is a primorial prime

11 (200560490131) is a primorial prime

13 (304250263527209) is a primorial prime

24 ([big (35 digits)]) is a primorial prime

66 ([big (131 digits)]) is a primorial prime

68 ([big (136 digits)]) is a primorial prime

75 ([big (154 digits)]) is a primorial prime

</pre>