C This subroutine computes the dot product of two REAL arrays
C (X and Y) of length SIZE.  The answer is communicated back
C via Z.

      SUBROUTINE DOTPROD (X, Y, Z, SIZE)

      IMPLICIT NONE
      INTEGER I, SIZE
      REAL X(SIZE), Y(SIZE), Z(SIZE)

      DO I = 1, SIZE
         Z(I) = X(I) * Y(I)
      ENDDO

      RETURN
      END


C The main program exercises DOTPROC

      PROGRAM TESTER

      IMPLICIT NONE
      INTEGER I, N, SIZE
      PARAMETER (SIZE=100)
      REAL A(SIZE), B(SIZE), C(SIZE)

      PRINT *, 'Please enter the number of elements in the arrays'
      READ *, N

      IF ((N .LT. 1) .OR. (N .GT. SIZE)) THEN
         PRINT *, 'That is a bad number'
         STOP
      ENDIF

      DO I = 1, N
         PRINT *, 'Enter element ', I, ' of A'
         READ *, A(I)
         PRINT *, 'Enter element ', I, ' of B'
         READ *, B(I)
      ENDDO

      PRINT *, 'A   = ', (A(I), I=1,N)
      PRINT *, 'B   = ', (B(I), I=1,N)

      CALL DOTPROD(A, B, C, N)

      PRINT *, 'A*B = ', (C(I), I=1,N)

      STOP
      END