.\" Copyright (c) 1985, 1991 Regents of the University of California.
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.\"     from: @(#)ieee.3	6.4 (Berkeley) 5/6/91
.\" %FreeBSD: src/lib/msun/man/ieee_test.3,v 1.5.2.4 2001/12/17 10:08:36 ru Exp %
.\"
.\" $FreeBSD$
.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 ライブラリ
.Ld libm
.Sh 書式
.In 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
これらの関数は、ユーザが
.St -ieee754
への適合をテストすることを可能にします。
それ以外の目的でのこれらの使用は推奨されません。
.Pp
.Fn logb x
および
.Fn logbf x
は、
.Fa x
の
.Fa n
乗を返します。ここでの
.Fa n
は、符号付き整数が倍精度浮動小数点に変換されたものです。
.Fn logb \*(Pm\*(If
= +\*(If;
.Fn logb 0
= -\*(If
で、0 による除算の例外を伴います。
.Pp
.Fn scalbn x n
および
.Fn scalbnf x n
は、指数操作により計算された
.Fa x Ns \(**(2** Ns Fa n )
を返します。
.Pp
.Fn significand x
および
.Fn significandf x
は、1 \(<= 
.Fa sig
< 2 の範囲で
.Fa x
:=
.Fa sig No \(** 2** Ns Fa n
となる時の、
.Fa sig
を返します。
.Fn significand x
および
.Fn significandf x
は、
.Fa x
が 0, \*(Pm\*(If, または \*(Na の時には定義されません。
.Sh 関連項目
.Xr ieee 3 ,
.Xr math 3
.Sh 規格
.St -ieee754