# What is a latex allergy definition

The limit is hardcoded into the object representation.

1. You can use a bit machine: the limit goes up to 246 — 3
2. You can break up your list into smaller chunks (use vectors of vectors)

## How can I loop over permutations?

In and higher, use . It is more than n times faster. n = 4; for (i = 1, n!, print( numtoperm(n, i) ))

## How can I loop over every subsets of S?

In and higher, you can use . It is a little faster. forsubset(#S, s, print( vecextract(S, s) )) for (i = 0, 2^#S — 1, print( vecextract(S, i) ))

## How can I loop over subsets of S with k elements?

In and higher, you can use . It is orders of magnitudes faster. forsubset([#S,k], s, print( vecextract(S, s) )) forvec( v=vector(k, i,[1,#S]), print(vecextract(S,v)), 2)

## How can I loop over partitions?

Use . Here is an exciting but much slower recursive implementation: aux(n, m, v) = { v = concat(v,m); if(!n, print(v), for(i=1, min(m,n), aux(n-i, i, v))); } partitionsgp(n) = for(i=1, n, aux(n-i, i, []))

## How can I loop over divisors of polynomials?

Use . It is not specific to integers.

Hardcoded Limits

## How to input n random bytes from /dev/urandom?

On a Unix system, you can for instance use the utility to suitably format the source:

RAND(n)= extern(Str(«echo 0x`od -x -An -N», n, » /dev/urandom`»)) ? RAND(8) %1 = ? RAND(8) %2 =

You can use as a seed for (the non-cryptographically secure PRNG) . For cryptographic uses, you should generate every random data directly from .

## How can I increase maximal recursion depth?

The maximal recursion depth is governed by the maximal stack space allocated to the gp process (not to be confused with gp’s stack). Use the following commands from the shell, before starting gp, to increase the process stack size to kbytes, say:

If your shell is sh-based (bash, ksh, sh, zsh):

ulimit -s

If your shell is csh-based (csh, tcsh):

limit stacksize

Timer

## Is there a tutorial for ‘extern’?

Here is a worked out example for Cremona’s mwrank.

Loops

## I desire more variables, is not enough

Since pari, only polynomial variables are limited, not user variables.

A polynomial variable springs into existence only when it is needed in an actual polynomial. I.e. creates a variable , but does not. Thus this limit should no longer be a problem.

It remains hardcoded into the object representation and cannot be easily increased. Note that on a bit machine the limit goes from 214 — 1 to 216 — 1.

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