MirBSD manpage: isnan(3)

ISNAN(3)                   BSD Programmer's Manual                    ISNAN(3)

NAME

     isnan - test for not-a-number

LIBRARY

     libc

SYNOPSIS

     #include <math.h>

     int
     isnan(real-floating x);

DESCRIPTION

     The isnan() macro determines whether its argument x is not-a-number
     ("NaN"). An argument represented in a format wider than its semantic type
     is converted to its semantic type first. The determination is then based
     on the type of the argument.

IEEE 754

     It is determined whether the value of x is a NaN.

VAX

     NaNs are not supported.

RETURN VALUES

     The isnan() macro returns a non-zero value if the value of x is a NaN.
     Otherwise 0 is returned.

SEE ALSO

     fpclassify(3), isfinite(3), isinf(3), isinff(3), isnanf(3), isnormal(3),
     math(3), signbit(3)

     IEEE Standard for Binary Floating-Point Arithmetic, Std 754-1985, ANSI.

STANDARDS

     The isnan() macro conforms to ISO/IEC 9899:1999 ("ISO C99").

MirBSD #10-current              March 5, 2004                                1