9.3.78 ISNAN (X)

Description:  Tests whether IEEE real (S_floating and T_floating) numbers are Not-a-Number (NaN) values. On OpenVMS systems, the compiler option specifying IEEE floating format must be set.  
Class:  Elemental function; Generic 
Arguments:  X 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

Consider the following:

  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..


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