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MODF(3P) POSIX Programmer's Manual MODF(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
modf, modff, modfl — decompose a floating-point number
#include <math.h>
double modf(double x, double *iptr);
float modff(float value, float *iptr);
long double modfl(long double value, long double *iptr);
The functionality described on this reference page is aligned with
the ISO C standard. Any conflict between the requirements described
here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
These functions shall break the argument x into integral and
fractional parts, each of which has the same sign as the argument. It
stores the integral part as a double (for the modf() function), a
float (for the modff() function), or a long double (for the modfl()
function), in the object pointed to by iptr.
Upon successful completion, these functions shall return the signed
fractional part of x.
If x is NaN, a NaN shall be returned, and *iptr shall be set to a
NaN.
If x is ±Inf, ±0 shall be returned, and *iptr shall be set to ±Inf.
No errors are defined.
The following sections are informative.
None.
The modf() function computes the function result and *iptr such that:
a = modf(x, iptr) ;
x == a+*iptr ;
allowing for the usual floating-point inaccuracies.
None.
None.
frexp(3p), isnan(3p), ldexp(3p)
The Base Definitions volume of POSIX.1‐2008, math.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 MODF(3P)
Pages that refer to this page: math.h(0p), tgmath.h(0p), frexp(3p)