MODF
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Index
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PROLOG
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.
NAME
modf,
modff,
modfl
--- decompose a floating-point number
SYNOPSIS
#include <math.h>
double modf(double x, double *iptr);
float modff(float value, float *iptr);
long double modfl(long double value, long double *iptr);
DESCRIPTION
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.1-2017 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.
RETURN VALUE
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.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
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.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
frexp(),
isnan(),
ldexp()
The Base Definitions volume of POSIX.1-2017,
<math.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
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.opengroup.org/unix/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 .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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