Add missing fmpz_mod_mpoly_compose_ functions

doc/source/fmpz_mod_mpoly.rst

@@ -436,6 +436,7 @@ Evaluation
     Return `1` for success and `0` for failure.
 
 .. function:: int fmpz_mod_mpoly_compose_fmpz_mod_mpoly_geobucket(fmpz_mod_mpoly_t A, const fmpz_mod_mpoly_t B, fmpz_mod_mpoly_struct * const * C, const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC)
+              int fmpz_mod_mpoly_compose_fmpz_mod_mpoly_horner(fmpz_mod_mpoly_t A, const fmpz_mod_mpoly_t B, fmpz_mod_mpoly_struct * const * C, const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC)
               int fmpz_mod_mpoly_compose_fmpz_mod_mpoly(fmpz_mod_mpoly_t A, const fmpz_mod_mpoly_t B, fmpz_mod_mpoly_struct * const * C, const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC)
 
     Set *A* to the evaluation of *B* where the variables are replaced by the corresponding elements of the array *C*.

src/fmpz_mod_mpoly.h

@@ -570,10 +570,19 @@ int fmpz_mod_mpoly_compose_fmpz_mod_mpoly_geobucket(fmpz_mod_mpoly_t A,
             const fmpz_mod_mpoly_t B, fmpz_mod_mpoly_struct * const * C,
             const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC);
 
+int fmpz_mod_mpoly_compose_fmpz_mod_mpoly_horner(fmpz_mod_mpoly_t A,
+            const fmpz_mod_mpoly_t B, fmpz_mod_mpoly_struct * const * C,
+            const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC);
+
 int fmpz_mod_mpoly_compose_fmpz_mod_mpoly(fmpz_mod_mpoly_t A,
             const fmpz_mod_mpoly_t B, fmpz_mod_mpoly_struct * const * C,
             const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC);
 
+void fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(fmpz_mod_mpoly_t A,
+            const fmpz_mod_mpoly_t B, const slong * c,
+            const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC);
+
+
 /* Multiplication ************************************************************/
 
 void fmpz_mod_mpoly_mul(fmpz_mod_mpoly_t A,

src/fmpz_mod_mpoly/compose_fmpz_mod_mpoly.c

@@ -64,14 +64,14 @@ int fmpz_mod_mpoly_compose_fmpz_mod_mpoly(
 matrix_no_good:
 
     fmpz_mat_clear(M);
-/*
+
     for (i = 0; i < ctxB->minfo->nvars; i++)
     {
         if (C[i]->length > 1)
         {
-            return nmod_mpoly_compose_nmod_mpoly_horner(A, B, C, ctxB, ctxAC);
+            return fmpz_mod_mpoly_compose_fmpz_mod_mpoly_horner(A, B, C, ctxB, ctxAC);
         }
     }
-*/
+
     return fmpz_mod_mpoly_compose_fmpz_mod_mpoly_geobucket(A, B, C, ctxB, ctxAC);
 }

src/fmpz_mod_mpoly/compose_fmpz_mod_mpoly_gen.c

@@ -0,0 +1,48 @@
+/*
+    Copyright (C) 2020 Daniel Schultz
+
+    This file is part of FLINT.
+
+    FLINT is free software: you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.  See <https://www.gnu.org/licenses/>.
+*/
+
+#include "fmpz_mat.h"
+#include "mpoly.h"
+#include "fmpz_mod_mpoly.h"
+
+/* evaluate B(x_1,...,x_n) at x_i = y_c[i], y_j are vars of ctxAC */
+void fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(fmpz_mod_mpoly_t A,
+            const fmpz_mod_mpoly_t B, const slong * c,
+            const fmpz_mod_mpoly_ctx_t ctxB, const fmpz_mod_mpoly_ctx_t ctxAC)
+{
+    fmpz_mat_t M;
+
+    if (B->length == 0)
+    {
+        fmpz_mod_mpoly_zero(A, ctxAC);
+        return;
+    }
+
+    fmpz_mat_init(M, ctxAC->minfo->nfields + 1, ctxB->minfo->nfields);
+    mpoly_compose_mat_gen(M, c, ctxB->minfo, ctxAC->minfo);
+
+    if (A == B)
+    {
+        fmpz_mod_mpoly_t T;
+        fmpz_mod_mpoly_init(T, ctxAC);
+        _fmpz_mod_mpoly_compose_mat(T, B, M, ctxB, ctxAC);
+        fmpz_mod_mpoly_swap(A, T, ctxAC);
+        fmpz_mod_mpoly_clear(T, ctxAC);
+    }
+    else
+    {
+        _fmpz_mod_mpoly_compose_mat(A, B, M, ctxB, ctxAC);
+    }
+
+    fmpz_mat_clear(M);
+
+    return;
+}