fpclassify

Name

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

Library

libm.lib

Synopsis

#include <math.h>

int fpclassify (real-floating x);

int isfinite (real-floating x);

int isinf (real-floating x);

int isnan (real-floating x);

int isnormal (real-floating x);

Detailed 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 non-zero value if and only if its argument has a finite (zero, subnormal, or normal) value. The isinf, isnan, and isnormal macros return non-zero if and only if x is an infinity, NaN, or a non-zero normalized number, respectively.

The symbol isnanf is provided as an alias to isnan for compatibility, and its use is deprecated.

Examples

#include <math.h>
void main()
{
   double x1 = 6.5, x2 = 2.25;
   int y;
   y = fpclassify( x1);
   /* Use the Predefine Macro to
      determine the Return Values
      interpretation
   */
   switch( y ){
   case FP_INFINITE: printf("%f is a Infinite Value\n", x1);break;
   case FP_NAN:   printf("%f is a NAN Value\n", x1);break;
        case FP_NORMAL:   printf("%f is a Normalized Floating point Value\n", x1);break;
        case FP_SUBNORMAL:printf("%f is a Subnormalized Floating point Number\n", x1);break;
        case FP_ZERO:     printf("%f is a Zero\n", x1);break;
        case default:     printf("%f is a Invalid Input", x1);break;
 }
   y = isfinite( x1 );
   printf( "isfinite(%f) = %d\n", x1,  y );
   y = isinf( x1);
   printf( "isinf(%f) = %d\n", x1 y );
   y = isnan( x1);
   printf( "isnan(%f) = %f\n", x1, y );
   y = isnormal( x1);
   printf( isnormal(%f) = %f\n", x1,  y );
}

Output

6.5 is a Normalized Floating point Value\n
isfinite(6.5) = 1
isinf(6.5)    = 1
isnan(6.5)    = 0
isnormal(6.5) = 1

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