Example 6.5

FORTRAN Version

!
      PROGRAM P68
!
      IMPLICIT NONE
      INTEGER :: J
      REAL :: X,Y
!
      INTERFACE
      FUNCTION GAUSS(X,U,SD)
      IMPLICIT NONE
      REAL, INTENT(IN) :: X,U,SD
      REAL :: GAUSS
      END FUNCTION GAUSS
      END INTERFACE
!
      PRINT *, 'This is Program >> P68  - GAUSS Function'
!
!     Example of using a function
!     on the RHS of an assignment statement
!
      X = 0.0
L1:   DO J =1,11  ! 11 steps in the positive X direction
         Y=5.0*GAUSS(X,0.0,1.0)+2.5
!
!     The Gaussian or Normal curve has
!     been scaled and translated
!
         PRINT *,X,Y
         X = X + 0.5     ! Increase X by a step of .5
      END DO L1
      STOP
      END PROGRAM P68
!
!     Example of writing a function
!
      FUNCTION GAUSS(X,U,SD)
      IMPLICIT NONE
      REAL, INTENT(IN) :: X,U,SD      
      REAL :: C,GAUSS
      C=1.0/(SD*SQRT(2.0*3.14159))
      GAUSS=C*EXP(-(X-U)**2/(2.0*SD**2))
      RETURN
      END FUNCTION GAUSS

              +--------------------------------------------------+
              |     32-bit Power for Lahey Computer Systems      |
              |   Phar Lap's 386|DOS-Extender(tm) Version 7.0    |
              |  Copyright (C) 1986-94 Phar Lap Software, Inc.   |
              |           Available Memory = 14880 Kb            |
              +--------------------------------------------------+


This is Program >> P68  - GAUSS Function
   0.000000        4.49471    
   0.500000        4.26033    
    1.00000        3.70985    
    1.50000        3.14759    
    2.00000        2.76995    
    2.50000        2.58764    
    3.00000        2.52216    
    3.50000        2.50436    
    4.00000        2.50067    
    4.50000        2.50008    
    5.00000        2.50001    

Pascal Version

PROGRAM p68 (input, output);
VAR
  y : REAL;

FUNCTION gauss ( x, u, sd : REAL ) : REAL;
VAR
  c : REAL;
BEGIN
  c := 1.0 / ( sd * sqrt ( 2.0 * 3.14159 ) );
  gauss := c * exp ( -sqr ( x - u ) / ( 2.0 * sqr ( sd ) ) )
END;

BEGIN
  y := 5.0 * gauss ( 2.5, 0.0, 1.0 ) + 9.5;
  writeln ( y )
END.

Last modified: 22/07/97