Matrixmultiplikation

      PROGRAM MATMUL
C
C  MULTIPLIKATION VON MATRIZEN
C

      IMPLICIT LOGICAL(A-Z)
      
      INTEGER N 
      PARAMETER (N = 1000)

      DOUBLE PRECISION   A(N, N), B(N,N), C(N,N)
      DOUBLE PRECISION   SPUR, SPUR1, CTH
      INTEGER I, J, K

C     ANFANGSWERTE SETZEN
      DO 100 I=1, N
         DO 110 J=1, N
            A(I,J) = I + J
            B(I,J) = I - J
 110     CONTINUE
         B(I,I) = 1.0
 100  CONTINUE

C     MATRIXMULTIPLIKATION
      DO 200 I = 1, N
         DO 210 J = 1, N
            C(I, J) = 0.0
            DO 220 K = 1, N
               C(I, J) = C(I, J) + A(I, K) * B(K, J)
 220        CONTINUE
 210     CONTINUE
 200  CONTINUE

C     TESTDATEN AUSGEBEN
      SPUR1 = N * (N+1)
      PRINT *, "SPUR THEORETISCH: ", SPUR1
      SPUR = 0.0
      DO 300 I = 1, N
         SPUR = SPUR + C(I,I)
 300  CONTINUE
      PRINT *, "SPUR            : ", SPUR

      CTH = 333331003.0D0
      PRINT *, "C(1,2) THEOR.   : ", CTH
      PRINT *, "C(1,2)          : ", C(1,2)

      END