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.\" from: @(#)floor.3 6.5 (Berkeley) 4/19/91
.\" $Id: fma.3,v 1.4 2004/12/20 21:35:45 scp Exp $
.\"
.Dd May 28, 2008
.Dt FMA 3
.Os
.Sh NAME
.Nm fma
.Nd multiply and add, then round
.Sh SYNOPSIS
.Fd #include
.Ft double
.Fn fma "double x" "double y" "double z"
.Ft long double
.Fn fmal "long double x" "long double y" "long double z"
.Ft float
.Fn fmaf "float x" "float y" "float z"
.Sh DESCRIPTION
The
.Fn fma
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 current rounding mode.
.Sh SPECIAL VALUES
.Fn fma "x" "y" "z"
returns a NaN and optionally raises the "invalid" floating-point
exception if one of x and y is infinite, the other is 0, and z is
a NaN.
.Pp
.Fn fma "x" "y" "z"
returns a NaN and raises the "invalid" floating-point
exception if one of x and y is infinite, the other is 0, and z is
not NaN.
.Pp
.Fn fma "x" "y" "z"
returns a NaN and raises the "invalid" floating-point
exception if x times y is an exact infinity, and z is also
an infinity but with the opposite sign.
.Sh SEE ALSO
.Xr fdim 3 ,
.Xr fmax 3 ,
.Xr fmin 3
.Sh STANDARDS
The
.Fn fma
functions conform to ISO/IEC 9899:1999(E).