User:Yeti

From Rosetta Code

AWK/Primes/FSOE[edit]

AWK/Primes/FSOE1[edit]

FSOE1 needs a number:set mapping and expressing this in AWK would blow up the code too much. (Or shorter: Maybe later.)

AWK/Primes/FSOE3[edit]

BEGIN {
n=2
while( n<100 ) {
if( n in L ) {
p=L[n]
del L[n]
} else {
p=n
printf n " "
}
npp=n+p
while( npp in L )
npp=npp+p
L[npp]=p
n++
}
print
}
Output:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 


BASH/Self Modyfying Code[edit]

$ . Thing-1033909978
$ type Thing 
Thing is a function
Thing () 
{ 
    local get='shift;local __=$1;shift;echo ${!__}' set='shift;__=$1;shift;local $__="$*";eval "$FUNCNAME () { local $(local | tr "\n" " "); $(type $FUNCNAME | tail +5)"' version=1033909978;
    eval ${!1}
}
$ Thing get version
1033909978
$ date [email protected]$(Thing get version) # ;-)
Sun Oct  6 13:12:58 UTC 2002
$ ##
$ ## add a new property 'show'
$ ##
$ Thing set show local
$ ##
$ ## try it
$ ##
$ Thing show
get='shift;local __=$1;shift;echo ${!__}'
set='shift;__=$1;shift;local $__="$*";eval "$FUNCNAME () { local $(local | tr "\n" " "); $(type $FUNCNAME | tail +5)"'
show=local
version=1033909978

Dc/Questions/DROP[edit]

TODO Drop top of stack without side effects

# assume there is a value in x[1337], e.g. "gold"
[gold] 1337 :x

# "trash" on the stack:
[trash]

# push x[1337] to x-stack
1337;x Sx
# deposit TOS in x[1337]
1337:
# top of x-stack to x[1337]
Lx 1337:

1337 ;x

[Stack: ]PAP f
Output:
Stack: 
gold

Sigh!

Is there really no simpler way to drop the top of stack that works for strings and numbers and in all versions of Dc?

Python/Primes/FSOE[edit]

Works with: Python version 2.x

This is a sequentialised variant of the well known sieve method (ab)using a dictionary as sparse array.

Alternatively you can describe it as finding the wheels and moving them on a tape. The only knowledge is to start looking 2 instead of starting with 1, but the original sieve does skip 1 too. 2 is not hard coded to be prime. The algorithm detects it as 1st prime and then puts the 2-wheel on the tape.

Python/Primes/FSOE1[edit]

Variant: A tape position can hold multiple wheels.

L = {}
n = 2
 
while 1:
 
if n in L:
P = L[n]
del L[n] # optional - saves some memory.
else:
print n
P = [n]
 
for p in P:
npp = n+p
if npp in L:
L[npp].add(p)
else:
L[npp] = set([p])
 
n += 1
Output:
2
3
5
7
11
13
17
19
23
29

...the program has to be terminated by the user e.g. by typing ctrl-c.

Python/Primes/FSOE3[edit]

Works with: Python version 2.x

Variant: A tape position can hold one wheel.

L = {}
n = 2
 
while 1:
 
if n in L:
P = L[n]
del L[n] # optional - saves some memory.
else:
P = n
print n
 
m = n+P
while m in L:
m += P
L[m] = P
 
n += 1
Output:
2
3
5
7
11
13
17
19
23
29

...the program has to be terminated by the user e.g. by typing ctrl-c.


My Favorite Languages
Language Proficiency
AWK ---
B ---
BASH ---
C ---
Dc ---
Spin ---