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79 lines
1.6 KiB
79 lines
1.6 KiB
/*
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* Copyright(C) 1999-2020 National Technology & Engineering Solutions
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* of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with
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* NTESS, the U.S. Government retains certain rights in this software.
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*
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* See packages/seacas/LICENSE for details
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*/
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#ifdef __STDC__
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#include <float.h>
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#endif
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/* Returns some machine/compiler specific values. */
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/* Note: These values might not be calculated precisely correctly.*/
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/* If you know them for your machine, replace this code! */
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void machine_params(double *double_epsilon, double *double_max)
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/* returns machine precision */
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/* returns largest double value */
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{
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#ifndef DBL_EPSILON
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double eps; /* machine precision */
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#endif
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#ifndef DBL_MAX
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#ifndef DBL_MIN
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double double_min; /* smallest double value */
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double min, min_prev; /* values halved to compute double_min */
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#endif
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double max; /* largest double precision value */
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#endif
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#ifndef DBL_EPSILON
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eps = 1.0 / 16.0;
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while (1.0 + eps > 1.0)
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eps /= 2.0;
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*double_epsilon = eps * 2.0;
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#else
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*double_epsilon = DBL_EPSILON;
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#endif
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#ifndef DBL_MAX
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#ifndef DBL_MIN
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min_prev = min = 1.0;
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while (min * 1.0 > 0) {
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min_prev = min;
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min /= 32.0;
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}
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min = min_prev;
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while (min * 1.0 > 0) {
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min_prev = min;
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min /= 2.0;
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}
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double_min = min_prev / (*double_epsilon);
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#else
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double_min = DBL_MIN;
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#endif
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max = 2.0 * (1.0 - *double_epsilon) / (double_min);
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/*
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two_max = max*2.0;
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while (two_max/2.0 == max) {
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max = two_max;
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two_max = max*2.0;
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}
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*/
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*double_max = max;
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#else
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*double_max = DBL_MAX;
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#endif
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}
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