modf(3) — Linux manual page

modf(3)                 Library Functions Manual                 modf(3)

NAME         top

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

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #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         top

       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         top

       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         top

       No errors occur.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │modf(), modff(), modfl()              │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       C99, POSIX.1-2001.

       The variant returning double also conforms to SVr4, 4.3BSD, C89.

SEE ALSO         top

       frexp(3), ldexp(3)

Linux man-pages 6.04           2023-03-30                        modf(3)

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

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