ALL: Add flint

external/flint-2.4.3/nmod_poly/div_root.c

@@ -0,0 +1,86 @@
+/*=============================================================================
+
+    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
+
+******************************************************************************/
+
+#include <gmp.h>
+#include "flint.h"
+#include "nmod_vec.h"
+#include "nmod_poly.h"
+
+mp_limb_t
+_nmod_poly_div_root(mp_ptr Q, mp_srcptr A, slong len, mp_limb_t c, nmod_t mod)
+{
+    mp_limb_t r, t;
+    slong i;
+
+    if (len < 2)
+        return UWORD(0);
+
+    t = A[len - 2];
+    r = Q[len - 2] = A[len - 1];
+
+    for (i = len - 2; i > 0; i--)
+    {
+        r = nmod_add(nmod_mul(r, c, mod), t, mod);
+        t = A[i-1];
+        Q[i-1] = r;
+    }
+
+    r = nmod_add(nmod_mul(r, c, mod), t, mod);
+    return r;
+}
+
+mp_limb_t
+nmod_poly_div_root(nmod_poly_t Q, 
+                 const nmod_poly_t A, mp_limb_t c)
+{
+    mp_limb_t rem;
+
+    slong len = A->length;
+
+    if (len == 0)
+    {
+        nmod_poly_zero(Q);
+        return UWORD(0);
+    }
+
+    if (len == 1)
+    {
+        rem = A->coeffs[0];
+        nmod_poly_zero(Q);
+        return rem;
+    }
+
+    if (c == 0)
+    {
+        rem = A->coeffs[0];
+        nmod_poly_shift_right(Q, A, 1);
+        return rem;
+    }
+
+    nmod_poly_fit_length(Q, len - 1);
+    rem = _nmod_poly_div_root(Q->coeffs, A->coeffs, len, c, Q->mod);
+    Q->length = len - 1;
+    return rem;
+}