Passing commands to PARI on Windows

[James Heinrich]

edit: This started off as a help-request thread, but I have solved my own problem while typing it. It may yet contain useful information, so I'll post anyways.


I have a code snippet (which I got from someone here, but I seem unable to find the original thread) for authenticating whether a factor actually divides a Mersenne exponent. And it works very nicely... but not on Windows.

On *nix, it does as expected:

# echo "Mod(2,2383)^397" | /usr/local/bin/gp -q
Mod(1, 2383)

But on Windows it just says back to me:

"Mod(2,2383)^397"

with quotes and everything. But it does work fine within PARI itself, it's just a command-passing issue.

C:\Users\User>"C:\Program Files (x86)\PARI\gp.exe" -q
(10:03) gp > Mod(2,2383)^397
Mod(1, 2383)

I had run into this problem before when trying to factor reported factors, and made these notes:

// fail: echo 'factor(1234)' | "C:\Program Files (x86)\PARI\gp.exe" -q :: ***   unused characters: 'factor(1234)'
// fail: echo "factor(1234)" | "C:\Program Files (x86)\PARI\gp.exe" -q :: %1 = "factor(1234)"
// work: echo factor(1234) | "C:\Program Files (x86)\PARI\gp.exe" -q

So Windows doesn't like quoted strings in this context, but does work just passing the raw command.

Except when you get to the current problem, because the caret is a special character:

C:\>echo Mod(2,2383)^397 | "C:\Program Files (x86)\PARI\gp.exe" -q
  ***   unused characters: Mod(2,2383)397
                                      ^---

So you might think escaping it would help, but no:

C:\>echo Mod(2,2383)^^397 | "C:\Program Files (x86)\PARI\gp.exe" -q
  ***   unused characters: Mod(2,2383)397
                                      ^---

Unless, that is, you double-escape it:

C:\Users\User>echo Mod(2,2383)^^^^397 | "C:\Program Files (x86)\PARI\gp.exe" -q
Mod(1, 2383)

So there you have it. On the rare chance that someone runs into this problem, I hope this saves you some headache.

[Xitami]

echo eval(" 2+2^2 ") | gp -q

[James Heinrich]

Oh, that works

Thanks!