**frexp**

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
These functions are used to split the number x into a normalized frac-
tion and an exponent which is stored in exp.
RETURN VALUE
These functions return 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 (exclusive),
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
For an explanation of the terms used in this section, see
**attributes(7)**.
+----------------------------+---------------+---------+
|Interface | Attribute | Value |
+----------------------------+---------------+---------+
|frexp(), frexpf(), frexpl() | Thread safety | MT-Safe |
+----------------------------+---------------+---------+
CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD, C89.
EXAMPLE
The program below produces results such as the following:
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 4.04 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/.
2015-04-19 **FREXP(3)**

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