### Table of Contents

# fdim

## NAME

fdim, fdimf, fdiml - compute positive difference between two floating-point numbers

## SYNOPSIS

c99 [ *flag*… ] *file*… **-lm** [ *library*… ]

#include <math.h>

**double fdim**(**double** *x*, **double** *y*);

**float fdimf**(**float** *x*, **float** *y*);

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

## DESCRIPTION

These functions determine the positive difference between their arguments. If *x* is greater than *y*, *x*−*y* is returned. If *x* is less than or equal to *y*, +0 is returned.

## RETURN VALUES

Upon successful completion, these functions return the positive difference value.

If *x*−*y* is positive and overflows, a range error occurs and **fdim()**, **fdimf()**, and **fdiml()** returns the value of the macro **HUGE_VAL**, **HUGE_VALF**, and **HUGE_VALL**, respectively.

If *x* or *y* is NaN, a NaN is returned.

## ERRORS

These functions will fail if:

**Range Error**

The result overflows.

If the integer expression (**math_errhandling** & **MATH_ERREXCEPT**) is non-zero, the overflow floating-point exception will be raised.

## USAGE

An application wanting to check for exceptions should call **feclearexcept**(**FE_ALL_EXCEPT**) before calling these functions. On return, if **fetestexcept**(**FE_INVALID** | **FE_DIVBYZERO** | **FE_OVERFLOW** | **FE_UNDERFLOW**) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

## ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

## SEE ALSO

**math.h**(3HEAD), **feclearexcept**(3M), **fetestexcept**(3M), **fmax**(3M), **fmin**(3M), attributes(7), standards(7)