xref: /netbsd/lib/libm/man/ieee_test.3 (revision 56b14ee0)

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.\"     from: @(#)ieee.3	6.4 (Berkeley) 5/6/91
.\"	$NetBSD: ieee_test.3,v 1.14 2017/07/03 21:32:50 wiz Exp $
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.Dd August 3, 2011
.Dt IEEE_TEST 3
.Os
.Sh NAME
.Nm logb ,
.Nm logbf ,
.Nm logbl ,
.Nm scalb ,
.Nm scalbf ,
.Nm significand ,
.Nm significandf
.Nd IEEE test functions
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn logb "double x"
.Ft float
.Fn logbf "float x"
.Ft long double
.Fn logbl "long double 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 DESCRIPTION
These functions allow users to test conformance to
.St -ieee754 .
Their use is otherwise not recommended.
.Pp
.Fn logb x
returns
.Fa x Ns 's exponent
.Fa n ,
a signed integer converted to double\-precision floating\-point.
.Fn logb \*(Pm\*(If
= +\*(If;
.Fn logb 0
= -\*(If with a division by zero exception.
.Pp
.Fn scalb x n
returns
.Fa x Ns \(**(2** Ns Fa n )
computed by exponent manipulation.
.Pp
.Fn significand x
returns
.Fa sig ,
where
.Fa x
:=
.Fa sig No \(** 2** Ns Fa n
with 1 \*[Le]
.Fa sig
< 2.
.Fn significand x
is not defined when
.Fa x
is 0, \*(Pm\*(If, or \*(Na.
.Sh SEE ALSO
.Xr math 3
.Sh STANDARDS
.St -ieee754