FPCLASSIFY (3)  C library functions  Unix Manual Pages  :man▋
fpclassify, isfinite, isinf, isnan, isnormal  "classify a floatingpoint number"
CONTENTS
Library Synopsis Description See Also Standards History
LIBRARY
.Lb libm
SYNOPSIS
.In math.h int fpclassify "realfloating x" int isfinite "realfloating x" int isinf "realfloating x" int isnan "realfloating x" int isnormal "realfloating x"
DESCRIPTION
The fpclassify macro takes an argument of x and returns one of the following manifest constants. 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)
STANDARDS
HISTORY
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