[PATCH] fix powmod(0,0,3) in INT and SINT

[Qian Yun]

This will make "0^0 mod 3" return 1 instead of 0, making it
consistent with the rest of fricas.

This will make 0^0 return 1 for ZMOD.

This will not affect the other user of powmod in
"rabinProvesComposite".

- Qian


diff --git a/src/algebra/integer.spad b/src/algebra/integer.spad
index 91bc0c46..a93d2f57 100644
--- a/src/algebra/integer.spad
+++ b/src/algebra/integer.spad
@@ -186,8 +186,8 @@
-- speeds up functions like 'primes'
powmod(x, n : %, p) ==
if negative? x then x := positiveRemainder(x, p)
- zero? x => 0
zero? n => 1
+ zero? x => 0
y : % := 1
z := x
repeat
diff --git a/src/algebra/si.spad b/src/algebra/si.spad
index 736abf2f..ac28e709 100644
--- a/src/algebra/si.spad
+++ b/src/algebra/si.spad
@@ -129,8 +129,8 @@

powmod(x, n, p) ==
if negative? x then x := positiveRemainder(x, p)
- zero? x => 0
zero? n => 1
+ zero? x => 0
y : % := 1
z := x
repeat

[Waldek Hebisch]

On Sat, May 30, 2026 at 02:13:03PM +0800, Qian Yun wrote:
> This will make "0^0 mod 3" return 1 instead of 0, making it
> consistent with the rest of fricas.
>
> This will make 0^0 return 1 for ZMOD.
>
> This will not affect the other user of powmod in
> "rabinProvesComposite".

Thanks, please commit.

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--
Waldek Hebisch