ALL: Add flint

external/flint-2.4.3/fq/ctx_init_modulus.c

@@ -0,0 +1,92 @@
+/*=============================================================================
+
+    This file is part of FLINT.
+
+    FLINT is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    FLINT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with FLINT; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+
+=============================================================================*/
+/******************************************************************************
+
+    Copyright (C) 2013 Mike Hansen
+
+******************************************************************************/
+
+#include <stdio.h>
+#include <string.h>
+
+#include "fq.h"
+#include "fq_poly.h"
+
+void
+fq_ctx_init_modulus(fq_ctx_t ctx, fmpz_mod_poly_t modulus, const char *var)
+{
+    slong nz;
+    int i, j;
+    fmpz* p;
+    fmpz_t inv;
+
+    p = &(modulus->p);
+
+    /* Count number of nonzero coefficients */
+    nz = 0;
+    for (i = 0; i < modulus->length; i++)
+    {
+        if (!fmpz_is_zero(modulus->coeffs + i))
+        {
+            nz += 1;
+        }
+    }
+
+    ctx->len = nz;
+    ctx->a = _fmpz_vec_init(ctx->len);
+    ctx->j = flint_malloc(ctx->len * sizeof(slong));
+
+    fmpz_init(inv);
+    fmpz_invmod(inv, modulus->coeffs + modulus->length - 1, p);
+
+    /* Copy the polynomial */
+    j = 0;
+    for (i = 0; i < modulus->length; i++)
+    {
+        if (!fmpz_is_zero(modulus->coeffs + i))
+        {
+            fmpz_mul(ctx->a + j, inv, modulus->coeffs + i);
+            fmpz_mod(ctx->a + j, ctx->a + j, p);
+            ctx->j[j] = i;
+            j++;
+        }
+    }
+
+    fmpz_clear(inv);
+
+    if (ctx->len < 6)
+        ctx->sparse_modulus = 1;
+    else
+        ctx->sparse_modulus = 0;
+
+    fmpz_init_set(fq_ctx_prime(ctx), p);
+
+    ctx->var = flint_malloc(strlen(var) + 1);
+    strcpy(ctx->var, var);
+
+    /* Set the modulus */
+    fmpz_mod_poly_init(ctx->modulus, fq_ctx_prime(ctx));
+    fmpz_mod_poly_set(ctx->modulus, modulus);
+
+    /* Precompute the inverse of the modulus */
+    fmpz_mod_poly_init(ctx->inv, fq_ctx_prime(ctx));
+    fmpz_mod_poly_reverse(ctx->inv, ctx->modulus, ctx->modulus->length);
+    fmpz_mod_poly_inv_series_newton(ctx->inv, ctx->inv, ctx->modulus->length);
+}