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3. Library calls (functions within program libraries)

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MODF

Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
Index  |  Return to Main Contents
 

NAME

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

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);

Link with -lm.

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 versions <= 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).
InterfaceAttributeValue
modf(), modff(), modfl() Thread safetyMT-Safe
 

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

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

SEE ALSO

frexp(3), ldexp(3)  

COLOPHON

This page is part of release 5.10 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
SEE ALSO
COLOPHON

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