ALL: Add flint

external/flint-2.4.3/fmpz_mod_poly/compose_horner.c

@@ -0,0 +1,108 @@
+/*=============================================================================
+
+    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 Sebastian Pancratz
+
+******************************************************************************/
+
+#include <gmp.h>
+#include "flint.h"
+#include "fmpz_mod_poly.h"
+
+void _fmpz_mod_poly_compose_horner(fmpz *res, const fmpz *poly1, slong len1, 
+                                              const fmpz *poly2, slong len2, 
+                                              const fmpz_t p)
+{
+    if (len1 == 1 || len2 == 0)
+    {
+        fmpz_set(res, poly1);
+    }
+    else
+    {
+        const slong alloc = (len1 - 1) * (len2 - 1) + 1;
+        slong i = len1 - 1, lenr = len2;
+        fmpz * t = _fmpz_vec_init(alloc);
+        
+        /*
+           Perform the first two steps as one, 
+             "res = a(m) * poly2 + a(m-1)".
+         */
+        {
+            _fmpz_mod_poly_scalar_mul_fmpz(res, poly2, len2, poly1 + i, p);
+            i--;
+            fmpz_add(res, res, poly1 + i);
+            if (fmpz_cmpabs(res, p) >= 0)
+                fmpz_sub(res, res, p);
+        }
+        while (i > 0)
+        {
+            i--;
+            _fmpz_mod_poly_mul(t, res, lenr, poly2, len2, p);
+            lenr += len2 - 1;
+            _fmpz_mod_poly_add(res, t, lenr, poly1 + i, 1, p);
+        }
+
+        _fmpz_vec_clear(t, alloc);
+    }
+}
+
+void fmpz_mod_poly_compose_horner(fmpz_mod_poly_t res, 
+                                  const fmpz_mod_poly_t poly1, 
+                                  const fmpz_mod_poly_t poly2)
+{
+    const slong len1 = poly1->length;
+    const slong len2 = poly2->length;
+
+    if (len1 == 0)
+    {
+        fmpz_mod_poly_zero(res);
+    }
+    else if (len1 == 1 || len2 == 0)
+    {
+        fmpz_mod_poly_set_fmpz(res, poly1->coeffs);
+    }
+    else
+    {
+        const slong lenr = (len1 - 1) * (len2 - 1) + 1;
+
+        if ((res != poly1) && (res != poly2))
+        {
+            fmpz_mod_poly_fit_length(res, lenr);
+            _fmpz_mod_poly_compose_horner(res->coeffs, poly1->coeffs, len1, 
+                                                       poly2->coeffs, len2,
+                                                       &(res->p));
+        }
+        else
+        {
+            fmpz *t = _fmpz_vec_init(lenr);
+
+            _fmpz_mod_poly_compose_horner(t, poly1->coeffs, len1,
+                                             poly2->coeffs, len2, &(res->p));
+            _fmpz_vec_clear(res->coeffs, res->alloc);
+            res->coeffs = t;
+            res->alloc  = lenr;
+            res->length = lenr;
+        }
+
+        _fmpz_mod_poly_set_length(res, lenr);
+        _fmpz_mod_poly_normalise(res);
+    }
+}