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DBLROUND.C
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C/C++ Source or Header
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1997-07-05
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/* +++Date last modified: 05-Jul-1997 */
/*
** DBLROUND.C - Rounds a double to the nearest whole number
** public domain by Ross Cottrell
*/
#include <float.h>
#include <limits.h>
#include "snipmath.h"
#if defined(__ZTC__)
#include <fltenv.h>
#define SAVEROUND() \
int fersave = fegetround(); \
fesetround(FE_TONEAREST)
#define RESTOREROUND() \
fesetround(fersave)
#else
#if !defined(FLT_ROUNDS) || (FLT_ROUNDS != 1)
#error FLT_ROUNDS needs to be defined to be 1
#endif
#define SAVEROUND()
#define RESTOREROUND()
#endif
double dround(double x)
{
Boolean_T flag;
static volatile double X;
SAVEROUND();
if (True_ == (flag = (x < 0.0)))
X = -x;
else X = x;
X += 1.0 / DBL_EPSILON;
X -= 1.0 / DBL_EPSILON;
RESTOREROUND();
return ((flag) ? -X : X);
}
#ifdef TEST
#include <stdio.h>
#include <stdlib.h>
main(int argc, char *argv[])
{
double val;
char *dummy;
while (--argc)
{
val = strtod((const char *)(*(++argv)), &dummy);
printf("dround(%g) = ", val);
printf("%.12g\n", dround(val));
}
return EXIT_SUCCESS;
}
#endif /* TEST */