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32.\" from: @(#)floor.3 6.5 (Berkeley) 4/19/91
33.\" $Id: fma.3,v 1.4 2004/12/20 21:35:45 scp Exp $
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35.Dd May 28, 2008
36.Dt FMA 3
37.Os
38.Sh NAME
39.Nm fma
40.Nd multiply and add, then round
41.Sh SYNOPSIS
42.Fd #include <math.h>
43.Ft double
44.Fn fma "double x" "double y" "double z"
45.Ft long double
46.Fn fmal "long double x" "long double y" "long double z"
47.Ft float
48.Fn fmaf "float x" "float y" "float z"
49.Sh DESCRIPTION
50The
51.Fn fma
52functions compute (x*y)+z, rounded as one ternary operation:
53they compute the value (as if) to infinite precision and round once
54to the result format, according to the current rounding mode.
55.Sh SPECIAL VALUES
56.Fn fma "x" "y" "z"
57returns a NaN and optionally raises the "invalid" floating-point
58exception if one of x and y is infinite, the other is 0, and z is
59a NaN.
60.Pp
61.Fn fma "x" "y" "z"
62returns a NaN and raises the "invalid" floating-point
63exception if one of x and y is infinite, the other is 0, and z is
64not NaN.
65.Pp
66.Fn fma "x" "y" "z"
67returns a NaN and raises the "invalid" floating-point
68exception if x times y is an exact infinity, and z is also
69an infinity but with the opposite sign.
70.Sh SEE ALSO
71.Xr fdim 3 ,
72.Xr fmax 3 ,
73.Xr fmin 3
74.Sh STANDARDS
75The
76.Fn fma
77functions conform to ISO/IEC 9899:1999(E).