From CFD-Wiki
!Sample program for solving Lid-driven cavity flow test using SIMPLE-algorithm
! solution of linear system of equations by Thomas algorithm modul
!Copyright (C) 2010 Michail Kiričkov
!Copyright (C) 2016 Michail Kiričkov, Kaunas University for Technology
!This program is free software; you can redistribute it and/or
!modify it under the terms of the GNU General Public License
!as published by the Free Software Foundation; either version 2
!of the License, or (at your option) any later version.
!This program is distributed in the hope that it will be useful,
!but WITHOUT ANY WARRANTY; without even the implied warranty of
!MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
!GNU General Public License for more details.
!You should have received a copy of the GNU General Public License
!along with this program; if not, write to the Free Software
!Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
!**********************************************************************
Subroutine TDMA_1(NF)
include 'icomm_1.f90'
DOUBLE PRECISION P(nx),Q(nx)
!-----------------------------------------------------------
Do 101 J = 2, NYmax
P(1) = 0.
Q(1) = F(1,j,nf)
P(NXmaxC) = 0.
Q(NXmaxC) = F(NXmaxC,j,nf)
! Forward Elimination
Do 10 i = 2,NXmaxC-1
temp = Ap(i,j,nf) - Aw(i,j) * P(i-1)
Spp= Sp(i,j,nf) + As(i,j) * F(i,j-1,nf) + &
An(i,j) * F(i,j+1,nf)
P(i) = Ae(i,j) / temp
Q(i) = (Spp + Aw(i,j)*Q(i-1)) / temp
10 continue
! Back Substitution
Do 20 i = NXmaxC-1,1,-1
F(i,j,nf) = P(i)*F(i+1,j,nf) + Q(i)
20 continue
101 continue
!-----------------------------------------------------------
Do 301 J = NYmax,2,-1
P(1) = 0.
Q(1) = F(1,j,nf)
P(NXmaxC) = 0.
Q(NXmaxC) = F(NXmaxC,j,nf)
! Forward Elimination
Do 32 i = 2,NXmaxC-1
temp = Ap(i,j,nf) - Aw(i,j) * P(i-1)
Spp= Sp(i,j,nf) + As(i,j) * F(i,j-1,nf) + &
An(i,j) * F(i,j+1,nf)
P(i) = Ae(i,j) / temp
Q(i) = (Spp + Aw(i,j)*Q(i-1)) / temp
32 continue
! Back Substitution
Do 30 i = NXmaxC-1,2,-1
F(i,j,nf) = P(i)*F(i+1,j,nf) + Q(i)
30 continue
301 continue
!--------------------------------------------------------------
Return
End
