SUBROUTINE RES (T, U, UPRIME, CJ, DELTA, IRES, RPAR, IPAR, 
     *                SENPARA)
C
C This is the user-supplied RES subroutine for this example.
C It computes the residuals for the 2-D discretized heat equation,
C with zero boundary values.
C
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)
      DIMENSION U(*), UPRIME(*), DELTA(*), RPAR(*), IPAR(*),
     *          SENPARA(*)
C
C Set problem constants using IPAR and RPAR.
      NEQ = IPAR(3)
      M = IPAR(4)
      COEFF = RPAR(2)
      M2 = M + 2
C
C Load U into DELTA, in order to set boundary values.
      DO 10 I = 1,NEQ
 10     DELTA(I) = U(I)
C
C Loop over interior points, and load residual values.
      DO 30 K = 1,M
        IOFF = M2*K
        DO 20 J = 1,M
          I = IOFF + J + 1
          TEMX = SENPARA(1)*(U(I-1)  + U(I+1)  - 2.0d0*u(i))
          TEMY = SENPARA(2)*(U(I-M2) + U(I+M2) - 2.0d0*u(i))
          DELTA(I) = UPRIME(I) - (TEMX + TEMY)*COEFF
 20       CONTINUE
 30     CONTINUE
C
      RETURN
C------------  End of Subroutine RESH  ---------------------------------
      END