ieee(3) - NetBSD Manual Pages

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IEEE(3)                   NetBSD Programmer's Manual                   IEEE(3)


NAME

     copysign, finite, ilogb, nextafter, remainder, scalbn - Functions for
     IEEE arithmetic


SYNOPSIS

     #include <math.h>

     double
     copysign(double x, double y);

     float
     copysignf(float x, float y);

     int
     finite(double x);

     int
     finitef(float x);

     int
     ilogb(double x);

     int
     ilogbf(float x);

     double
     nextafter(double x, double y);

     float
     nextafterf(float x, float y);

     double
     remainder(double x, double y);

     float
     remainderf(float x, float y);

     double
     scalbn(double x, int n);

     float
     scalbnf(float x, int n);


DESCRIPTION

     These functions are required or recommended by IEEE Std754-1985.

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

     finite() returns the value 1 just when -infinity < x < +infinity; other-
     wise a zero is returned (when |x| = infinity or x is NaN

     ilogb() returns x's exponent n, in integer format.  ilogb(+-infinity) re-
     turns INT_MAX and ilogb(0) returns INT_MIN.

     nextafter() returns the next machine representable number from x in di-
     rection y.

     remainder() 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 remainder(x, 0) and remainder(infinity, 0) are invalid operations
     that produce a NaN.


     scalbn() returns x*(2**n) computed by exponent manipulation.


SEE ALSO

     math(3)


HISTORY

     The ieee functions appeared in 4.3BSD.


STANDARDS

     IEEE Std754-1985

4.4BSD                           Feb 25, 1994                                2