ISNAN

Elemental Intrinsic Function (Generic): Tests whether IEEE® real (S_floating and T_floating) numbers are Not-a-Number (NaN) values.

Syntax

result = ISNAN (x)

x
(Output) Must be of type real.

Results:

The result is of type default logical. The result is .TRUE. if x is an IEEE NaN; otherwise, the result is .FALSE..

Examples

  LOGICAL A
  DOUBLE PRECISION B
  ...
  A = ISNAN(B)

A is assigned the value .TRUE. if B is an IEEE NaN; otherwise, the value assigned is .FALSE..