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Manual Reference Pages  - fpclassify (3)

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fpclassify, isfinite, isnormal, isnan - floating-point classification macros

CONTENTS

Synopsis
Description
Note

#include <math.h> 



int fpclassify(x); 



int isfinite(x); 



int isnormal(x); 



int isnan(x); 



int isinf(x); 

Floating point numbers can have special values, such as infinite or NaN. With the macro fpclassify(x) you can find out what type x is. The macro takes any floating-point expression as argument. The result takes one of the following values:

FP_NAN	x is "Not a Number".
FP_INFINITE
	x is either plus or minus infinity.
FP_ZERO
	x is zero.
FP_SUBNORMAL
	x is too small to be represented in normalized format.
FP_NORMAL
	if nothing of the above is correct that it must be a normal floating-point number.
The other macros provide a short answer to some standard questions.
isfinite(x)
	(fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
isnormal(x)
	(fpclassify(x) == FP_NORMAL)
isnan(x)
	(fpclassify(x) == FP_NAN)
isinf(x)
	(fpclassify(x) == FP_INFINITE)

C99

isgreater(3), isinf(3)

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