.\" Copyright (c) 1985 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)ieee.3m	6.2 (Berkeley) 5/12/86
.\"
.TH IEEE 3  "May 12, 1986"
.UC 6
.SH NAME
ieee, copysign, remainder, finite, logb, ilogb, scalb \- copysign, remainder, exponent manipulations
.SH SYNOPSIS
.nf
.ft B
#include <math.h>

double copysign(double \fIx\fP, double \fIy\fP)
double remainder(double \fIx\fP, double \fIy\fP)
int finite(double \fIx\fP)
double logb(double \fIx\fP)
double ilogb(double \fIx\fP)
double scalb(double \fIx\fP, double \fIy\fP)
double scalbn(double \fIx\fP, int \fIy\fP)
.ft R
.fi
.SH DESCRIPTION
These functions are required for, or recommended by the IEEE standard
754 for floating\-point arithmetic.
.PP
Copysign(x, y)
returns x with its sign changed to y's.
.PP
Remainder(x, y) returns the remainder r := x \- n\(**y
where n is the integer nearest the exact value of x/y;
moreover if |n\|\-\|x/y|\|\ =\ \|1/2 then n is even.  Consequently
the remainder is computed exactly and |r|\ \(<=\ |y|/2.
.PP
.nf
.ta \w'Finite(x)'u+1n
Finite(x)	= 1 just when \-Inf < x < +Inf,
	= 0 otherwise	(when |x| = Inf or x is NaN)
.DT
.fi
.PP
Logb(x) returns x's exponent n,
a signed integer converted to double\-precision floating\-point and so
chosen that 1\0\(<=\0|x|/2**n\0<\02 unless x = 0 or
.ig \" Minix is a
(only on machines that conform to IEEE 754)
..
|x| = Inf
or x lies between 0 and the Underflow Threshold; see below under "BUGS".
.PP
Ilogb(x) is like logb(x), but better.
.PP
Scalb(x, n) = x\(**(2**n) computed, for integer n, without first computing
2**n.
.PP
Scalbn(x, n) is like scalb(x, n), but better.
.PP
Logb and scalb are provided in the Sun FDLIBM to pass IEEE test suites.
They are not recommended.  Use ilogb and scalbn instead.
.SH SEE ALSO
.BR floor (3),
.BR math (3).
.SH AUTHOR
Kwok\-Choi Ng