Tribblix: manual page: fma.3m

FMA(3M) Mathematical Library Functions FMA(3M)

NAME

fma, fmaf, fmal - floating-point multiply-add

SYNOPSIS

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double fma(double x, double y, double z);

float fmaf(float x, float y, float z);

long double fmal(long double x, long double y, long double z);

DESCRIPTION

These functions compute (x * y) + z, rounded as one ternary
operation. They compute the value (as if) to infinite precision and
round once to the result format, according to the rounding mode
characterized by the value of FLT_ROUNDS.

RETURN VALUES

Upon successful completion, these functions return (x * y) + z,
rounded as one ternary operation.

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

If x multiplied by y is an exact infinity and z is also an infinity
but with the opposite sign, a domain error occurs and a NaN is
returned.

If one of x and y is infinite, the other is 0, and z is not a NaN, a
domain error occurs and a NaN is returned.

If x*y is not 0*Inf nor Inf*0 and z is a NaN, a NaN is returned.

ERRORS

These functions will fail if:

Domain Error
The value of x*y+z is invalid or the value x*y is
invalid.

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

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