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