Examples

Example 1: Use your own version of TAN:

       EXTERNAL TAN 
       T = TAN( 45.0 ) 
       ... 
       END 
       FUNCTION TAN( X ) 
       ... 
       RETURN 
       END 

Example 2: Pass a user-defined function name as an argument:

       REAL AREA, LOW, HIGH 
       EXTERNAL FCN 
       ... 
       CALL RUNGE ( FCN, LOW, HIGH, AREA ) 
       ... 
       END 

       FUNCTION FCN( X ) 
       ... 
       RETURN 
       END 

       SUBROUTINE RUNGE ( F, X0, X1, A ) 
       ... 
       RETURN 
       END