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Annotation of OpenXM_contrib/gmp/mpf/sqrt.c, Revision 1.1.1.1

1.1       maekawa     1: /* mpf_sqrt -- Compute the square root of a float.
                      2:
                      3: Copyright (C) 1993, 1994, 1996 Free Software Foundation, Inc.
                      4:
                      5: This file is part of the GNU MP Library.
                      6:
                      7: The GNU MP Library is free software; you can redistribute it and/or modify
                      8: it under the terms of the GNU Library General Public License as published by
                      9: the Free Software Foundation; either version 2 of the License, or (at your
                     10: option) any later version.
                     11:
                     12: The GNU MP Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
                     15: License for more details.
                     16:
                     17: You should have received a copy of the GNU Library General Public License
                     18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20: MA 02111-1307, USA. */
                     21:
                     22: #include "gmp.h"
                     23: #include "gmp-impl.h"
                     24:
                     25: void
                     26: #if __STDC__
                     27: mpf_sqrt (mpf_ptr r, mpf_srcptr u)
                     28: #else
                     29: mpf_sqrt (r, u)
                     30:      mpf_ptr r;
                     31:      mpf_srcptr u;
                     32: #endif
                     33: {
                     34:   mp_size_t usize;
                     35:   mp_ptr up, tp;
                     36:   mp_size_t prec;
                     37:   mp_exp_t tsize, rexp;
                     38:   TMP_DECL (marker);
                     39:
                     40:   usize = u->_mp_size;
                     41:   if (usize <= 0)
                     42:     {
                     43:       usize = 1 - 1 / (usize == 0);    /* Divide by zero for negative OP.  */
                     44:       r->_mp_size = usize;     /* cheat flow by using usize here */
                     45:       r->_mp_exp = 0;
                     46:       return;
                     47:     }
                     48:
                     49:   TMP_MARK (marker);
                     50:
                     51:   prec = r->_mp_prec;
                     52:   rexp = (u->_mp_exp + 1) >> 1;        /* round towards -inf */
                     53:   tsize = 2 * prec + (u->_mp_exp & 1);
                     54:
                     55:   up = u->_mp_d;
                     56:   tp = (mp_ptr) TMP_ALLOC (tsize * BYTES_PER_MP_LIMB);
                     57:
                     58:   if (usize > tsize)
                     59:     {
                     60:       up += usize - tsize;
                     61:       usize = tsize;
                     62:       MPN_COPY (tp, up, tsize);
                     63:     }
                     64:   else
                     65:     {
                     66:       MPN_ZERO (tp, tsize - usize);
                     67:       MPN_COPY (tp + (tsize - usize), up, usize);
                     68:     }
                     69:
                     70:   mpn_sqrtrem (r->_mp_d, NULL, tp, tsize);
                     71:
                     72:   r->_mp_size = (tsize + 1) / 2;
                     73:   r->_mp_exp = rexp;
                     74:   TMP_FREE (marker);
                     75: }