fdim(), fdimf(), fdiml()

Compute the positive difference between two floating-point numbers

Synopsis:

#include <math.h>

double fdim( double x,
             double y );

float fdimf( float x,
             float y );

long double fdiml( long double x,
                   long double y );

Arguments:

x, y: The numbers that you want to compute the difference between.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

The fdim(), fdimf(), and fdiml() functions compute the positive difference between two floating-point numbers. If x is greater than y, then these function return x - y. If x is less than or equal to y, these functions return +0.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

Call feclearexcept(FE_ALL_EXCEPT) before calling fdim(), fdimf(), or fdiml().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

Returns:

The positive difference.

If:	These functions return:	Errors:
`x` - `y` is positive and overflows	Inf	FE_OVERFLOW
The correct value would cause underflow	The correct value, after rounding	—
`x` or `y` is NaN	NaN	—

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

Classification:

ANSI, POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	No
Thread	Yes