CTITLEMASOLV -- SOLVE TRIDIAGONAL MATRIX                                00000010
C***********************************************************************
C                 COPYRIGHT ATLANTIC RICHFIELD COMPANY 1991            *
C***********************************************************************
CA    AUTHOR               RALPH MCMILLAN                               00000020
CA    DESIGNER             RALPH MCMILLAN                               00000030
CA    LANGUAGE             S/370 FORTRAN H                              00000040
CA    WRITTEN              01-10-77                                     00000050
C     REVISED                                                           00000060
C                                                                       00000070
CA                                                                      00000080
CA                                                                      00000090
CA    CALL MASOLV (A, E, DEN, N, T, D)                                  00000100
CA         INPUT      A = OFF DIAGONAL ELEMENTS FROM TRI-DIAGONAL   R4  00000110
CA         INPUT      E = AUX ARRAY CALCULATED IN MAINVT            R4  00000120
CA         INPUT    DEN = AUX ARRAY CALCULATED IN MAINVT            R4  00000130
CA         INPUT      N = NUMBER OF ELEMENTS IN A, E, DEN, T, AND D I4  00000140
CA         OUTPUT     T = SOLUTION OF TRI-DIAGONAL SYSTEM           R4  00000150
CA         IN/OUT     D = RIGHT HAND SIDE OF TRI-DIAGONAL SYSTEM    R4  00000160
CA                                                                      00000170
CA                                                                      00000180
CA    THIS ROUTINE SOLVES A TRIDIAGONAL MATRIX.                         00000190
CAEND                                                                   00000200
C                                                                       00000220
C     EJECT                                                             00000230
C                                                                       00000240
C     LOCAL VARIABLES AND CONSTANTS  (INTERNAL TO SUBROUTINE).          00000250
C                                                                       00000260
C     NM1    = N - 1                                                I4  00000270
C                                                                       00000280
      SUBROUTINE MASOLV (A, E, DEN, N, T, D)                            00000290
C                                                                       00000300
      IMPLICIT INTEGER (A-Z)                                            00000310
C                                                                       00000320
C                                                                       00000330
C     REAL ARRAYS IN PARAMETER LIST.                                    00000340
      REAL         A      (1)                                           00000350
      REAL         D      (1)                                           00000360
      REAL         E      (1)                                           00000370
      REAL       DEN      (1)                                           00000380
      REAL         T      (1)                                           00000390
C                                                                       00000400
C                                                                       00000410
      NM1 = N - 1                                                       00000420
C                                                                       00000430
      D(1) = 0.                                                         00000440
C                                                                       00000450
          DO                                                        10  00000460
     *    I = 2, NM1                                                    00000470
          D(I) = (D(I) - A(I) * D(I-1)) / DEN(I)                        00000480
C                                                                       00000490
   10     CONTINUE                                                      00000500
C                                                                       00000510
      T(N) = D(NM1) / (1.0 - E(NM1))                                    00000520
C                                                                       00000530
          DO                                                        20  00000540
     *    J = 1, NM1                                                    00000550
          I = N - J                                                     00000560
          T(I) = E(I) * T(I+1) + D(I)                                   00000570
C                                                                       00000580
   20     CONTINUE                                                      00000590
C                                                                       00000600
      RETURN                                                            00000610
      END                                                               00000620