NFFT
3.4.1
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kernel
util
float.c
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/*
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* Copyright (c) 2002, 2017 Jens Keiner, Stefan Kunis, Daniel Potts
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*
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* This program is free software; you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option) any later
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* version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "infft.h"
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R Y(float_property)(
const
float_property p)
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{
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const
R base = FLT_RADIX;
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const
R eps = NFFT_EPSILON;
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const
R t = MANT_DIG;
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const
R emin = MIN_EXP;
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const
R emax = MAX_EXP;
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const
R prec = eps * base;
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static
R rmin = K(1.0);
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static
R rmax = K(1.0);
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const
R rnd = FLTROUND;
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static
R sfmin = K(-1.0);
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static
short
first = TRUE;
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if
(first)
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{
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/* Compute rmin */
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{
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const
INT n = 1 - MIN_EXP;
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INT i;
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for
(i = 0; i < n; i++)
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rmin /= base;
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}
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/* Compute rmax */
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{
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INT i;
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rmax -= eps;
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for
(i = 0; i < emax; i++)
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rmax *= base;
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}
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/* Compute sfmin */
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{
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R small = K(1.0) / rmax;
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sfmin = rmin;
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if
(small >= sfmin)
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sfmin = small * (eps + K(1.0));
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}
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first = FALSE;
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}
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if
(p == NFFT_SAFE__MIN)
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return
sfmin;
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else
if
(p == NFFT_BASE)
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return
base;
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else
if
(p == NFFT_PRECISION)
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return
prec;
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else
if
(p == NFFT_MANT_DIG)
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return
t;
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else
if
(p == NFFT_FLTROUND)
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return
rnd;
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else
if
(p == NFFT_E_MIN)
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return
emin;
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else
if
(p == NFFT_R_MIN)
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return
rmin;
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else
if
(p == NFFT_E_MAX)
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return
emax;
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else
if
(p == NFFT_R_MAX)
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return
rmax;
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else
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CK(0
/* cannot happen */
);
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return
K(-1.0);
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}
/* dlamch_ */
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R Y(prod_real)(R *vec, INT d)
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{
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INT t;
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R prod;
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prod = K(1.0);
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for
(t = 0; t < d; t++)
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prod *= vec[t];
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return
prod;
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}
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