modf(3) — Linux manual page

modf(3)                 Library Functions Manual                 modf(3)

NAME

       modf, modff, modfl - extract signed integral and fractional
       values from floating-point number

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #include <math.h>

       double modf(double x, double *iptr);
       float modff(float x, float *iptr);
       long double modfl(long double x, long double *iptr);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       modff(), modfl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       These functions break the argument x into an integral part and a
       fractional part, each of which has the same sign as x.  The
       integral part is stored in the location pointed to by iptr.

RETURN VALUE

       These functions return the fractional part of x.

       If x is a NaN, a NaN is returned, and *iptr is set to a NaN.

       If x is positive infinity (negative infinity), +0 (-0) is
       returned, and *iptr is set to positive infinity (negative
       infinity).

ERRORS

       No errors occur.

ATTRIBUTES

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌─────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                           │ Attribute     │ Value   │
       ├─────────────────────────────────────┼───────────────┼─────────┤
       │ modf(), modff(), modfl()            │ 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.

SEE ALSO

       frexp(3), ldexp(3)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                        modf(3)

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

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