fp_class(3C)

NAME
     fp_class, fp_class_d, fp_class_f - classes of IEEE floating-point values

     fp_class_l - classes of long double floating-point values

SYNOPSIS
     #include <fp_class.h>

     int fp_class_d(double x);

     int fp_class_f(float x);

     int fp_class_l(long double x);

DESCRIPTION
     (Note that the long double routines are only valid for the MIPSpro
     compilers.)  Long double function fp_class_l has been renamed to be
     compliant with the ANSI-C standard, however to be backward compatible, it
     may still be called with the name fp_class_q.

     These routines are used to determine the class of IEEE or long double
     floating-point values.  They return one of the constants in the file
     <fp_class.h> and never cause an exception even for signaling NaN's.
     These routines are to implement the recommended function class(x) in the
     appendix of the IEEE 754-1985 standard for binary floating-point
     arithmetic.

     The constants in <fp_class.h> refer to the following classes of values:

     Constant       Class
     FP_SNAN        Signaling NaN (Not-a-Number)
     FP_QNAN        Quiet NaN (Not-a-Number)
     FP_POS_INF     +oo (positive infinity)
     FP_NEG_INF     -oo (negative infinity)
     FP_POS_NORM    positive normalized non-zero
     FP_NEG_NORM    negative normalized non-zero
     FP_POS_DENORM  positive denormalized
     FP_NEG_DENORM  negative denormalized
     FP_POS_ZERO    +0.0 (positive zero)
     FP_NEG_ZERO    -0.0 (negative zero)

     Note that these functions are distinct from the SVR4 function fpclass
     (see isnan(3C)).

SEE ALSO
     isnan(3C).
     ANSI/IEEE Std 754-1985, IEEE Standard for Binary Floating- Point
     Arithmetic

     In the case of long doubles, non-zero numbers less than 2**-916 in
     absolute value are classified as denormalized, since one of the numbers
     used in their representation may be a denormal double.