

FP_INFINITE  Indicates that x is an infinite number. 
FP_NAN  Indicates that x is not a number (NaN). 
FP_NORMAL  Indicates that x is a normalized number. 
FP_SUBNORMAL  
Indicates that x is a denormalized number.  
FP_ZERO  Indicates that x is zero (0 or 0). 
The isfinite macro returns a nonzero value if and only if its argument has a finite (zero, subnormal, or normal) value. The isinf, isnan, and isnormal macros return nonzero if and only if x is an infinity, NaN, or a nonzero normalized number, respectively.
The symbol isnanf is provided as an alias to isnan for compatibility, and its use is deprecated. Similarly, finite and finitef are deprecated versions of isfinite.
isgreater(3), math(3), signbit(3)
The fpclassify, isfinite, isinf, isnan, and isnormal macros conform to isoC99.
The fpclassify, isfinite, isinf, isnan, and isnormal macros were added in
.Fx 5.1 . BSD 3 introduced isinf and isnan functions, which accepted
.Vt double arguments; these have been superseded by the macros described above.
Visit the GSP FreeBSD Man Page Interface.
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