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 (con-
       sult 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
       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,  Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                      MODF(3P)