Merge pull request flintlib#2115 from thofma/main

fix: fmpz_mod_poly for modulus 1
albinahlback · Nov 24, 2024 · cb7513b · cb7513b
2 parents 487785c + 4b84512
commit cb7513b
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Showing 2 changed files with 9 additions and 6 deletions.
diff --git a/src/fmpz_mod_poly.h b/src/fmpz_mod_poly.h
@@ -202,11 +202,7 @@ int fmpz_mod_poly_is_one(const fmpz_mod_poly_t poly, const fmpz_mod_ctx_t FLINT_
    return poly->length == 1 && poly->coeffs[0] == WORD(1);
 }
 
-FMPZ_MOD_POLY_INLINE
-int fmpz_mod_poly_is_gen(const fmpz_mod_poly_t op, const fmpz_mod_ctx_t FLINT_UNUSED(ctx))
-{
-    return op->length == 2 && op->coeffs[1] == WORD(1) && op->coeffs[0] == WORD(0);
-}
+int fmpz_mod_poly_is_gen(const fmpz_mod_poly_t op, const fmpz_mod_ctx_t ctx);
 
 int fmpz_mod_poly_is_unit(const fmpz_mod_poly_t op, const fmpz_mod_ctx_t ctx);
 

diff --git a/src/fmpz_mod_poly/attributes.c b/src/fmpz_mod_poly/attributes.c
@@ -12,8 +12,15 @@
 #include "fmpz_mod.h"
 #include "fmpz_mod_poly.h"
 
+int fmpz_mod_poly_is_gen(const fmpz_mod_poly_t op, const fmpz_mod_ctx_t ctx)
+{
+    return (*fmpz_mod_ctx_modulus(ctx) == UWORD(1)) ||
+           (op->length == 2 && op->coeffs[1] == WORD(1) && op->coeffs[0] == WORD(0));
+}
+
 /* bogus for non-prime modulus */
 int fmpz_mod_poly_is_unit(const fmpz_mod_poly_t op, const fmpz_mod_ctx_t ctx)
 {
-    return (op->length == 1) && fmpz_mod_is_invertible(op->coeffs + 0, ctx);
+    return (*fmpz_mod_ctx_modulus(ctx) == UWORD(1)) ||
+           (op->length == 1 && fmpz_mod_is_invertible(op->coeffs + 0, ctx));
 }