FDIM(3) | Library Functions Manual | FDIM(3)

# NAME

`fdim`, `fdimf`, `fdiml` — positive difference functions

# SYNOPSIS

Math Library (libm, -lm)
`#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

The `fdim`(), `fdimf`(), and `fdiml`() functions return the positive difference between x and y. That is, if x-y is positive, then x-y is returned. If either x or y is an NaN, then an NaN is returned. Otherwise, the result is `+0.0`.

Overflow or underflow may occur if the exact result is not representable in the return type. No other exceptions are raised.

# SEE ALSO

fabs(3), fmax(3), fmin(3)

# STANDARDS

The `fdim`(), `fdimf`(), and `fdiml`() functions conform to ISO/IEC 9899:1999 (“ISO C99”).

# HISTORY

These routines first appeared in OpenBSD 4.5.

June 7, 2025 | Debian