isnan(S)

Syntax

   

   include <ieeefp.h>
   

   int isnand (double dsrc);
   

   int isnanf (float fsrc);
   

   int finite (double dsrc);
   

   fpclass_t fpclass (double dsrc);
   

   int unordered (double dsrc1, double dsrc2);
   

   include <math.h>
   

   int isnan (double dsrc);

Description

isnanf is implemented as a macro included in the ieeefp.h header file.

fpclass returns the class that dsrc belongs to. The 10 possible classes are as follows:

FP_SNAN

signaling NaN

FP_QNAN

quiet NaN

FP_NINF

negative infinity

FP_PINF

positive infinity

FP_NDENORM

negative denormalized non-zero

FP_PDENORM

positive denormalized non-zero

FP_NZERO

negative zero

FP_PZERO

positive zero

FP_NNORM

negative normalized non-zero

FP_PNORM

positive normalized non-zero

finite returns true (1) if the argument dsrc is neither infinity nor NaN; otherwise it returns false (0).

unordered returns true (1) if one of its two arguments is unordered with respect to the other argument. This is equivalent to reporting whether either argument is NaN. If neither of the arguments is NaN, false (0) is returned.

None of these routines generates exceptions, even for signaling NaNs.

See also

Standards conformance

Intel386 Binary Compatibility Specification, Edition 2 (iBCSe2) .