# ?isnan

Tests input for `NaN`.

## Syntax

val = sisnan( sin )

val = disnan( din )

## Description

This logical routine returns .TRUE. if its argument is NaN, and .FALSE. otherwise.

## Input Parameters

sin

  REAL for sisnan

  Input to test for NaN.

din

  DOUBLE PRECISION for disnan

  Input to test for NaN.

## Output Parameters

val

  Logical. Result of the test.

Parent topic: Auxiliary Routines