MODF(3P) | POSIX Programmer's Manual | MODF(3P) |

# 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>**

*x*

**, double ***

*iptr*

**);**

*value*

**, float ***

*iptr*

**);**

*value*

**, long double ***

*iptr*

**);**

# DESCRIPTION

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 IEEE Std 1003.1-2001,

*<math.h>*

# COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .2003 | IEEE/The Open Group |