| 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..