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 correspond-
ing 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
double modf(double x, double *iptr);
float modff(float value, float *iptr);
long double modfl(long double value, long double *iptr);
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.
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.
frexp(), isnan(), ldexp(), the Base Definitions volume of IEEE Std 1003.1-2001, <math.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- 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 .
/The Open Group 2003 MODF(3P)