58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
/* mpf_reldiff -- Generate the relative difference of two floats.
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Copyright 1996, 2001, 2004, 2005 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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/* The precision we use for d = x-y is based on what mpf_div will want from
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the dividend. It calls mpn_tdiv_qr to produce a quotient of rprec+1
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limbs. So rprec+1 == dsize - xsize + 1, hence dprec = rprec+xsize. */
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void
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mpf_reldiff (mpf_t rdiff, mpf_srcptr x, mpf_srcptr y)
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{
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if (UNLIKELY (SIZ(x) == 0))
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{
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mpf_set_ui (rdiff, (unsigned long int) (mpf_sgn (y) != 0));
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}
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else
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{
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mp_size_t dprec;
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mpf_t d;
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TMP_DECL;
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TMP_MARK;
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dprec = PREC(rdiff) + ABSIZ(x);
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ASSERT (PREC(rdiff)+1 == dprec - ABSIZ(x) + 1);
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PREC(d) = dprec;
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PTR(d) = TMP_ALLOC_LIMBS (dprec + 1);
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mpf_sub (d, x, y);
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SIZ(d) = ABSIZ(d);
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mpf_div (rdiff, d, x);
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TMP_FREE;
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}
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}
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