Matrix task

REAL,PARAMETER :: P = 0.0001, A_PARAM = P + 31.0, B_PARAM = 3*P - 29.0
      REAL A(8,8), A_SOURCE(8,8), E(8,8), B(8), B_SOURCE(8), B_TEMP(8), WORK(8), COND, COND_CACHE, NORM_1, NORM_2
      INTEGER NDIM/8/,N/8/,IPVT(8)
      DATA A/A_PARAM, -7., -7., -4., -8., -4., -1.,  0., &
                 -7., 27., -4., -4.,  0.,  -1, -4., -7., &
                 -7., -4., 31., -8., -7.,  0., -3., -2., &
                 -4., -4., -8., 39., -4., -7., -7., -5., &
                 -8.,  0., -7., -4., 29., -7., -2., -1., &
                 -4., -1.,  0., -7., -7., 25., -1., -5., &
                 -1., -4., -3., -7., -2., -1., 20., -2., &
                 0., -7., -2., -5., -1., -5., -2., 22./
      A_SOURCE = A;

      DATA B/B_PARAM, -2., -104., 198., 29., 59., -71., -54./
      B_SOURCE = B
      PRINT 101,((A(I,J),J=1,N),B(I),I=1,N)


      E = 0
      DO i=1, N
        E(i,i) = 1.0
      END DO

      CALL DECOMP(NDIM,N,A,COND,IPVT,WORK)
      PRINT 102,COND
      COND_CACHE = COND
      CONDP1=COND+1.0
      IF(CONDP1.EQ.COND) PRINT 103
      IF(CONDP1.EQ.COND) STOP

      CALL SOLVE(NDIM,N,A,B,IPVT)
      B_TEMP = B
      !PRINT 105,(B(I),I=1,N)


      A = A_SOURCE
      B = B_SOURCE
      CALL DECOMP(NDIM,N,A,COND,IPVT,WORK)
      DO i=1, N
        CALL SOLVE(NDIM,N,A,E(i,1:N),IPVT)
      END DO

      write (*,106 ) (E(i,1:N), i = 1, N)
      B_SOURCE = matmul(E,B)
      write (*,104) B_SOURCE !X1
      write (*,105) B_TEMP  !X2
      !write (*,104) ABS(B_SOURCE-B_TEMP) !X1

      NORM_1 = MAXVAL(ABS(B_SOURCE - B_TEMP))
      NORM_2 = MAXVAL(ABS(B_SOURCE))

      DIFF = NORM_1 / NORM_2
      write(*,"(/5X,'DIFF = ', E12.5)") DIFF
      write(*,"(/5X,'COND = ', E12.5)") COND
      write(*,"(//5X,'RESULT = ', E12.5)") DIFF/COND



      STOP

  101 FORMAT(13X,'A',92X,'B',/8(/5X,8F11.1, 5X, F11.1))
  102 FORMAT(/5X,'COND=',E12.5)
  103 FORMAT(5X,'MATRIX IS SINGULAR')
  104 FORMAT(/13X,'X1',8(/5X,F15.7))
  105 FORMAT(/13X,'X2',8(/5X,F15.7))
  106 FORMAT(/13X,'A^(-1)',8(/5X,8F15.7))
  107 FORMAT(/13X,'DIFF',8(/5X,8F15.7))

      END