isnan(3C)

isnan, isnand, isnanf, finite, fpclass, unordered -- determine type of floating-point number

Synopsis

   
   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

isnan, isnand, and isnanf return true (1) if the argument dsrc or fsrc is NaN; otherwise they return false (0). The functionality of isnan is identical to that of isnand.

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.

References

fpgetround(3C), intro(3)