frexp (3) - Linux Manuals
frexp: convert floating-point number to fractional
frexp, frexpf, frexpl - convert floating-point number to fractional and integral components
#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)):
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTIONThese functions are used to split the number x into a normalized fraction and an exponent which is stored in exp.
RETURN VALUEThese 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 (negative infinity) is returned, and the value of *exp is unspecified.
ERRORSNo errors occur.
ATTRIBUTESFor an explanation of the terms used in this section, see attributes(7).
|frexp(), frexpf(), frexpl()||Thread safety||MT-Safe|
CONFORMING TOC99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD, C89.
EXAMPLESThe program below produces results such as the following:
$ ./a.out 2560 frexp(2560, &e) = 0.625: 0.625 * 2ha12 = 2560 $ ./a.out -4 frexp(-4, &e) = -0.5: -0.5 * 2ha3 = -4
Program source#include <math.h> #include <float.h> #include <stdio.h> #include <stdlib.h>
main(int argc, char *argv)
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