x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
frexp(3) Library Functions Manual frexp(3)
NAME
frexp, frexpf, frexpl - convert floating-point number to fractional and
integral components
LIBRARY
Math library (libm, -lm)
SYNOPSIS
#include <math.h>
double frexp(double x, int *exp);
float frexpf(float x, int *exp);
long double frexpl(long double x, int *exp);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
frexpf(), frexpl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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 at-
tributes(7).
+--------------------------------------------+---------------+---------+
|Interface | Attribute | Value |
+--------------------------------------------+---------------+---------+
|frexp(), frexpf(), frexpl() | Thread safety | MT-Safe |
+--------------------------------------------+---------------+---------+
STANDARDS
C11, POSIX.1-2008.
HISTORY
C99, POSIX.1-2001.
The variant returning double also conforms to SVr4, 4.3BSD, C89.
EXAMPLES
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 <float.h>
#include <math.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)
Linux man-pages 6.04 2023-03-30 frexp(3)
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