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.\"     from: @(#)ieee.3	6.4 (Berkeley) 5/6/91
.\"	%Id: ieee_test.3,v 1.4 1997/02/22 15:09:36 peter Exp %
.\"
.Dd March 10, 1994
.Dt IEEE_TEST 3
.Os 
.Sh 名称
.Nm logb ,
.Nm logbf ,
.Nm scalb ,
.Nm scalbf ,
.Nm significand ,
.Nm significandf
.Nd IEEEテスト関数
.Sh 書式
.Fd #include <math.h>
.Ft double 
.Fn logb "double x"
.Ft float 
.Fn logbf "float x"
.Ft double 
.Fn scalb "double x" "double n"
.Ft float 
.Fn scalbf "float x" "float n"
.Ft double
.Fn significand "double x"
.Ft float
.Fn significandf "float x"
.Sh 解説
これらの関数でユーザは
.St -ieee754
への適合性のテストができます。
それ以外の目的での使用は推奨されません。
.Pp
.Fn logb x
と
.Fn logbf x
は、
.Fa x
の
.Fa n
乗で符号付き整数を倍精度浮動小数点に変換して返します。
.Fn logb \*(Pm\*(If
= +\*(If;
.Fn logb 0 
= -\*(If
ゼロ除算による例外が発生します。
.Pp
.Fn scalbn x n
と
.Fn scalbnf x n
は
指数操作により計算される
.Fa x Ns \(**(2** Ns Fa n )
を返します。
.Pp
.Fn significand x
と
.Fn significandf x
は
1 \(<= 
.Fa sig
< 2 の範囲のとき
.Fa sig
を返します。このとき、
.Fa x 
:= 
.Fa sig No \(** 2** Ns Fa n
です。
.Fn significand x
と
.Fn significandf x
は
.Fa x
が
0, \*(Pm\*(If
または
\*(Na
のとき定義されません。
.Pp
.Sh 関連項目
.Xr ieee 3 ,
.Xr math 3

.Sh 規格
.St -ieee754