Content-type: text/html Man page of fma

fma

Section: Mathematical Library Functions (3M)
Updated: 12 Jul 2006
Index Return to Main Contents
 

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

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard
MT-LevelMT-Safe

 

SEE ALSO

feclearexcept(3M), fetestexcept(3M), math.h(3HEAD), attributes(5), standards(5)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUES
ERRORS
USAGE
ATTRIBUTES
SEE ALSO

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Time: 02:39:34 GMT, October 02, 2010