HP-UX Reference (11i v2 03/08) - 3 Library Functions A-M (vol 6)

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modf(3M) modf(3M)

NAME

modf( ), modff( ), modﬂ( ), modfw( ), modfq( ) - decompose ﬂoating-point number

SYNOPSIS

#include <math.h>

double modf(double x, double *iptr);

Itanium(R)-based System Only

float modff(float x, float *iptr);

long double modfl(long double x, long double *iptr);

extended modfw(extended x, extended *iptr);

quad modfq(quad x, quad *iptr);

DESCRIPTION

The modf() function breaks 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 in the object pointed to by iptr .

Itanium-based System Only

modff() is a float version of modf(); it takes float and float * arguments and returns a

float result.

modfl() is a long double version of modf(); it takes long double and long double *

arguments and returns a long double result.

modfw() is an extended version of modf(); it takes extended and extended * arguments and

returns an extended result.

modfq() is equivalent to modfl() on HP-UX systems.

USAGE

To use (for Itanium-based systems)

modff(), compile either with the default -Ae option or with the -Aa

option.

To use (for Itanium-based systems)

modfl(), modfw(),ormodfq(), compile either with the default

-Ae option or with the -Aa and -D_HPUX_SOURCE

options.

To use (for Itanium-based systems)

modfw() or modfq(), compile also with the -fpwidetypes

option.

To use these functions, make sure your program includes

<math.h>, and link in the math library by

specifying -lm on the compiler or linker command line.

For more information, see the HP-UX Floating-Point Guide.

RETURN VALUE

modf(±x,iptr) returns a result with the same sign as x.

modf(±Inf,iptr) returns ±0 and stores ±Inf in the object pointed to by iptr.

modf(NaN,iptr) stores a NaN in the object pointed to by iptr and returns a NaN.

ERRORS

No errors are deﬁned.