IEEE(3M)                COMMAND REFERENCE                IEEE(3M)



NAME
     ieee, copysign, drem, finite, logb, scalb - copysign,
     remainder, exponent

SYNOPSIS
     #include <math.h>

     double copysign (x, y)
     double x, y;

     double drem (x, y)
     double x, y;

     int finite (x)
     double x;

     double logb (x)
     double x;

     double scalb (x, n)
     double x;
     int n;

DESCRIPTION
     These functions are required for, or recommended by the IEEE
     standard 754 for floating point arithmetic.

     Copysign (x, y)
                returns x with its sign changed to y's.

     Drem (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.  But drem (x,0) is exceptional;
                see the DIAGNOSTICS section.

     Finite (x) = 1 just when  -infinity < x < +infinity,
                = 0 otherwise (when  |x| = infinity or x is NaN)

     Logb (x)   returns x's exponent n, a signed integer
                converted to double-precision floating-point and
                so chosen that  1 < |x|/2**n < 2

     Scalb (x, n)
                = x*(2**n) computed, for integer n, without first
                computing 2**n.

DIAGNOSTICS
     Drem (x, 0) and drem (infinity, y) are undefined; errno is
     set to EDOM.



Printed 4/6/89                                                  1

IEEE(3M)                COMMAND REFERENCE                IEEE(3M)



     Logb is undefined when x is zero or negative; errno is set
     to EDOM.

     Scalb is undefined when the correct value would overflow;
     errno is set to ERANGE.

SEE ALSO
     intro(3m) and frexp(3c).















































Printed 4/6/89                                                  2

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