Merge pull request flintlib#2114 from thofma/th/nmodmpoly

fix: nmod_mpoly with modulus 1
albinahlback · Nov 24, 2024 · 487785c · 487785c
2 parents a8f9854 + 14c1be8
commit 487785c
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Showing 3 changed files with 10 additions and 1 deletion.
diff --git a/src/nmod_mpoly/gen.c b/src/nmod_mpoly/gen.c
@@ -16,6 +16,12 @@ void nmod_mpoly_gen(nmod_mpoly_t A, slong var, const nmod_mpoly_ctx_t ctx)
 {
     flint_bitcnt_t bits;
 
+    if (ctx->mod.n == UWORD(1))
+    {
+        nmod_mpoly_zero(A, ctx);
+        return;
+    }
+
     bits = mpoly_gen_bits_required(var, ctx->minfo);
     bits = mpoly_fix_bits(bits, ctx->minfo);
     nmod_mpoly_fit_length_reset_bits(A, 1, bits, ctx);

diff --git a/src/nmod_mpoly/is_gen.c b/src/nmod_mpoly/is_gen.c
@@ -15,6 +15,9 @@
 int nmod_mpoly_is_gen(const nmod_mpoly_t A,
                                          slong var, const nmod_mpoly_ctx_t ctx)
 {
+    if (ctx->mod.n == UWORD(1))
+        return 1;
+
     if (A->length != WORD(1))
         return 0;
 

diff --git a/src/nmod_mpoly/test/t-gen.c b/src/nmod_mpoly/test/t-gen.c
@@ -23,7 +23,7 @@ TEST_FUNCTION_START(nmod_mpoly_gen, state)
         slong len, exp_bits, k1, k2;
         ulong modulus;
 
-        modulus = UWORD(2) + n_randint(state, -UWORD(2));
+        modulus = UWORD(1) + n_randint(state, -UWORD(2));
         nmod_mpoly_ctx_init_rand(ctx, state, 20, modulus);
         if (ctx->minfo->nvars < 1)
         {