x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
FREXP(3) Linux Programmer's Manual FREXP(3)
NAME
frexp, frexpf, frexpl - convert floating-point number to fractional and
integral components
SYNOPSIS
#include <math.h>
double frexp(double x, int *exp);
float frexpf(float x, int *exp);
long double frexpl(long double x, int *exp);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
frexpf(), frexpl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
DESCRIPTION
The frexp() function is used to split the number x into a normalized
fraction and an exponent which is stored in exp.
RETURN VALUE
The frexp() function returns the normalized fraction. If the argument
x is not zero, the normalized fraction is x times a power of two, and
its absolute value is always in the range 1/2 (inclusive) to 1 (exclu-
sive), that is, [0.5,1).
If x is zero, then the normalized fraction is zero and zero is stored
in exp.
If x is a NaN, a NaN is returned, and the value of *exp is unspecified.
If x is positive infinity (negative infinity), positive infinity (nega-
tive infinity) is returned, and the value of *exp is unspecified.
ERRORS
No errors occur.
ATTRIBUTES
Multithreading (see pthreads(7))
The frexp(), frexpf(), and frexpl() functions are thread-safe.
CONFORMING TO
C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
4.3BSD, C89.
EXAMPLE
The program below produces results such as the following:
$ ./a.out 2560
frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
$ ./a.out -4
frexp(-4, &e) = -0.5: -0.5 * 2^3 = -4
Program source
#include <math.h>
#include <float.h>
#include <stdio.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{
double x, r;
int exp;
x = strtod(argv[1], NULL);
r = frexp(x, &exp);
printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n",
x, r, r, FLT_RADIX, exp, x);
exit(EXIT_SUCCESS);
}
SEE ALSO
ldexp(3), modf(3)
COLOPHON
This page is part of release 3.69 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
http://www.kernel.org/doc/man-pages/.
2013-08-06 FREXP(3)
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