@c ----------------------------------------------------------------------
@node modf, math
@subheading Syntax

@example
#include <math.h>

double modf(double x, double *pint);
@end example

@subheading Description

@code{modf} breaks down @var{x} into its integer portion (which it
stores in @var{*pint}) and the remaining fractional portion, which it
returns.  Both integer and fractional portions have the same sign as
@var{x}, except if @var{x} is a negative zero, in which case the integer
part is a positive zero.

@subheading Return Value

The fractional portion.  If @var{x} is @code{Inf} or @code{NaN}, the
return value is zero, the integer portion stored in @var{*pint} is the
same as the value of @var{x}, and @code{errno} is set to @code{EDOM}.

@subheading Portability

@portability ansi, posix