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frexp(3) — Linux manual page

NAME \|LIBRARY \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|ATTRIBUTES \|STANDARDS \|HISTORY \|EXAMPLES \|SEE ALSO \|COLOPHON

frexp(3)                 Library Functions Manualfrexp(3)

NAME top

       frexp, frexpf, frexpl - convert floating-point number to       fractional and integral components

LIBRARY top

       Math library (libm,-lm)

SYNOPSIS top

#include <math.h>double frexp(doublex, int *e);float frexpf(floatx, int *e);long double frexpl(long doublex, int *e);   Feature Test Macro Requirements for glibc (seefeature_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 top

       These functions are used to split the numberx into a normalized       fraction and an exponent which is stored ine.

RETURN VALUE top

       These functions return the normalized fraction.  If the argumentx       is not zero, the normalized fraction isx 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).       Ifx is zero, then the normalized fraction is zero and zero is       stored ine.       Ifx is a NaN, a NaN is returned, and the value of*e is       unspecified.       Ifx is positive infinity (negative infinity), positive infinity       (negative infinity) is returned, and the value of*e is       unspecified.

ERRORS top

       No errors occur.

ATTRIBUTES top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────────────────┬───────────────┬─────────┐       │Interface│Attribute│Value│       ├──────────────────────────────────────┼───────────────┼─────────┤       │frexp(),frexpf(),frexpl()          │ Thread safety │ MT-Safe │       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

       C11, POSIX.1-2008.

HISTORY top

       C99, POSIX.1-2001.       The variant returningdouble also conforms to SVr4, 4.3BSD, C89.

EXAMPLES top

       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 = -4Program source       #include <float.h>       #include <math.h>       #include <stdio.h>       #include <stdlib.h>       int       main(int argc, char *argv[])       {           double x, r;           int e;           x = strtod(argv[1], NULL);           r = frexp(x, &e);           printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n", x, r, r, 2, e, x);           exit(EXIT_SUCCESS);       }

COLOPHON top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-07-19frexp(3)

Pages that refer to this page:ldexp(3), modf(3)

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