float.c
/*
* Copyright (c) 2002, 2017 Jens Keiner, Stefan Kunis, Daniel Potts
*
* This program 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.
*
* This program 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
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "infft.h"
R Y(float_property)(const float_property p)
{
const R base = FLT_RADIX;
const R eps = NFFT_EPSILON;
const R t = MANT_DIG;
const R emin = MIN_EXP;
const R emax = MAX_EXP;
const R prec = eps * base;
static R rmin = K(1.0);
static R rmax = K(1.0);
const R rnd = FLTROUND;
static R sfmin = K(-1.0);
static short first = TRUE;
if (first)
{
/* Compute rmin */
{
const INT n = 1 - MIN_EXP;
INT i;
for (i = 0; i < n; i++)
rmin /= base;
}
/* Compute rmax */
{
INT i;
rmax -= eps;
for (i = 0; i < emax; i++)
rmax *= base;
}
/* Compute sfmin */
{
R small = K(1.0) / rmax;
sfmin = rmin;
if (small >= sfmin)
sfmin = small * (eps + K(1.0));
}
first = FALSE;
}
if (p == NFFT_SAFE__MIN)
return sfmin;
else if (p == NFFT_BASE)
return base;
else if (p == NFFT_PRECISION)
return prec;
else if (p == NFFT_MANT_DIG)
return t;
else if (p == NFFT_FLTROUND)
return rnd;
else if (p == NFFT_E_MIN)
return emin;
else if (p == NFFT_R_MIN)
return rmin;
else if (p == NFFT_E_MAX)
return emax;
else if (p == NFFT_R_MAX)
return rmax;
else
CK(0 /* cannot happen */);
return K(-1.0);
} /* dlamch_ */
R Y(prod_real)(R *vec, INT d)
{
INT t;
R prod;
prod = K(1.0);
for (t = 0; t < d; t++)
prod *= vec[t];
return prod;
}