freebsd-dev/lib/msun/man/ieee_test.3

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.\"     from: @(#)ieee.3	6.4 (Berkeley) 5/6/91
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.Dd March 10, 1994
.Dt IEEE_TEST 3
.Os 
.Sh NAME
.Nm logb ,
.Nm logbf ,
.Nm scalb ,
.Nm scalbf ,
.Nm significand ,
.Nm significandf
.Nd IEEE test functions
.Sh SYNOPSIS
.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 DESCRIPTION
These functions allow users to test conformance to 
.St -ieee754 .
Their use is not otherwise recommended.
.Pp
.Fn logb x
and
.Fn logbf x
return
.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 scalbn x n
and
.Fn scalbnf x n
return
.Fa x Ns \(**(2** Ns Fa n )
computed by exponent manipulation.
.Pp
.Fn significand x 
and
.Fn significandf x 
return
.Fa sig ,
where 
.Fa x 
:= 
.Fa sig No \(** 2** Ns Fa n
with 1 \(<= 
.Fa sig
< 2.
.Fn significand x
and
.Fn significandf x
are not defined when 
.Fa x
is 0, \*(Pm\*(If, or \*(Na.
.Sh SEE ALSO
.Xr ieee 3 ,
.Xr math 3

.Sh STANDARDS
.St -ieee754