ALL: Add flint

external/flint-2.4.3/fmpz_mod_poly/compose_mod_horner.c

@@ -0,0 +1,141 @@
+/*=============================================================================
+
+    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) 2011 Fredrik Johansson
+   Copyright (C) 2012 Lina Kulakova
+
+******************************************************************************/
+
+#include <gmp.h>
+#include "flint.h"
+#include "fmpz_vec.h"
+#include "fmpz_mod_poly.h"
+#include "ulong_extras.h"
+
+void
+_fmpz_mod_poly_compose_mod_horner(fmpz * res, const fmpz * f, slong lenf, const fmpz * g,
+                                              const fmpz * h, slong lenh, const fmpz_t p)
+{
+    slong i, len;
+    fmpz * t;
+
+    if (lenh == 1)
+        return;
+
+    if (lenf == 1)
+    {
+        fmpz_set(res, f);
+        return;
+    }
+
+    if (lenh == 2)
+    {
+        _fmpz_mod_poly_evaluate_fmpz(res, f, lenf, g, p);
+        return;
+    }
+
+    len = lenh - 1;
+    i = lenf - 1;
+    t = _fmpz_vec_init(2 * lenh - 3);
+
+    _fmpz_mod_poly_scalar_mul_fmpz(res, g, len, f + i, p);
+    i--;
+    if (i >= 0)
+    {
+        fmpz_add(res, res, f + i);
+        fmpz_mod(res, res, p);
+    }
+
+    while (i > 0)
+    {
+        i--;
+        _fmpz_mod_poly_mulmod(t, res, len, g, len, h, lenh, p);
+        _fmpz_mod_poly_add(res, t, len, f + i, 1, p);
+    }
+
+    _fmpz_vec_clear(t, 2 * lenh - 3);
+}
+
+void
+fmpz_mod_poly_compose_mod_horner(fmpz_mod_poly_t res, const fmpz_mod_poly_t poly1,
+                         const fmpz_mod_poly_t poly2, const fmpz_mod_poly_t poly3)
+{
+    fmpz_t inv3;
+    slong len1 = poly1->length;
+    slong len2 = poly2->length;
+    slong len3 = poly3->length;
+    slong len = len3 - 1;
+    slong vec_len = FLINT_MAX(len3 - 1, len2);
+
+    fmpz * ptr2;
+
+    if (len3 == 0)
+    {
+        flint_printf("Exception (fmpz_mod_poly_compose_mod_horner). Division by zero \n");
+        abort();
+    }
+
+    if (len1 == 0 || len3 == 1)
+    {
+        fmpz_mod_poly_zero(res);
+        return;
+    }
+
+    if (len1 == 1)
+    {
+        fmpz_mod_poly_set(res, poly1);
+        return;
+    }
+
+    if (res == poly3 || res == poly1)
+    {
+        fmpz_mod_poly_t tmp;
+        fmpz_mod_poly_init(tmp, &res->p);
+        fmpz_mod_poly_compose_mod_horner(tmp, poly1, poly2, poly3);
+        fmpz_mod_poly_swap(tmp, res);
+        fmpz_mod_poly_clear(tmp);
+        return;
+    }
+
+    ptr2 = _fmpz_vec_init(vec_len);
+
+    if (len2 <= len3 - 1)
+    {
+        _fmpz_vec_set(ptr2, poly2->coeffs, len2);
+        _fmpz_vec_zero(ptr2 + len2, vec_len - len2);
+    }
+    else
+    {
+        fmpz_init(inv3);
+        fmpz_invmod(inv3, poly3->coeffs + len, &res->p);
+        _fmpz_mod_poly_rem(ptr2, poly2->coeffs, len2,
+                           poly3->coeffs, len3, inv3, &res->p);
+        fmpz_clear(inv3);
+    }
+
+    fmpz_mod_poly_fit_length(res, len);
+    _fmpz_mod_poly_compose_mod_horner(res->coeffs,
+        poly1->coeffs, len1, ptr2, poly3->coeffs, len3, &res->p);
+    _fmpz_mod_poly_set_length(res, len);
+    _fmpz_mod_poly_normalise(res);
+
+    _fmpz_vec_clear(ptr2, vec_len);
+}