isnand(3)isnand(3)NAME
fpclass, isnand, isnanf - Related miscellaneous IEEE arithmetic func‐
tions.
SYNOPSIS
#include <ieeefp.h>
fpclass_t fpclass (double x); int isnand (double x);
int isnanf (float x);
LIBRARY
SVR4 Library (libsvr4)
DESCRIPTION
The fpclass() function determines the class of an IEEE floating-point
value. This returns one of the constants in the file <fpclass.h> and
never cause an exception, even for signaling NaNs. 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 +infinity
FP_NEG_INF −infinity
FP_POS_NORM Positive normalized
FP_NEG_NORM Negative normalized
FP_POS_DENORM Positive denormalized
FP_NEG_DENORM Negative denormalized
FP_POS_ZERO +0.0 (positive zero)
FP_NEG_ZERO −0.0 (negative zero)
─────────────────────────────────────────────────────
The isnand(), and isnanf() functions return the value 1 (True) if x is
NaN (the IEEE floating point reserved not-a-number value); otherwise,
it returns the value 0 (False).
These routines need to be compiled with the -ieee flag.
isnanf() function has a macro definition in the ieeefp.h header file.
This definition comes into play when the _STDC_ macro is undefined.
RELATED INFORMATIONdrem(3), logb(3), scalb(3), rint(3), sqrt(3), and ANSI/IEEE Std
754-1985, IEEE Standard for Binary Floating-Point Arithmetic
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isnand(3)