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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,  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 .