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to this bug and change the status back to "Open".

The gpm function gpm_powm() doesn't work !! 

For example:

$x = gmp_init(10);
$y = gmp_init(15);
$m = gmp_init(20);

$assoc = gmp_powm($x,$y,$m);

gmp_powm($x,$y,$m)) doesn't return anything.

What do you mean with 'doesn't return anything'? Does it not return a 'Resource id'?
Anyway, your calculation returns 0 (10^15=1000000000000000, 1000000000000000%20=0). Is that what you mean?

What does the following sample script print for you:
<?php
echo ($x = gmp_init(3))."\n";
echo ($y = gmp_init(3))."\n";
echo ($m = gmp_init(20))."\n";

echo ($assoc = gmp_powm($x,$y,$m))."\n";
echo gmp_strval($assoc)."\n";
?>

Also, what's your configure line and your version of gmp?

I'm using PHP 4.1.2.

No, it doesn't return a 'Resource id'. The script doesn't work. It's sounds like an erro on this function because, if I comment it, the script work friendly. 

On my configure line I added --with-gmp.

You still failed to mention which version of gmp you are using.

Lets try this again:

What is your ENTIRE configure line.  What version of GMP are you using?  What does that script print for you?  Does it print an error message?

I don't know ... Is gmp comming with php ?

No.

I'm bogusifying until you can answer the questions we asked you. Without those answers we cannot help you any further. Feel free to re-open if you have the necessary information.