modf(P)                                                 modf(P)





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 IEEE Std 1003.1-2001
       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 vol-
       ume 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  Operat-
       ing System Interface (POSIX), The Open Group Base Speci-
       fications Issue 6, Copyright (C) 2001-2003 by the Insti-
       tute  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 .



POSIX                         2003                      modf(P)
