Element-by-element techniques and Parallel Programming - The Boundary Element Method with Programming - page 204

Elements_1
!------------------------------------------------------------
! Add azimuthal integral for infinite regions
!------------------------------------------------------------
IF(Nreg == 2) THEN
DO m=1, Nodes
DO n=1, N_dof
IF(Ndest(m,n) == 0)CYCLE
k=Ndest(m,n)
Diag(k,n) = Diag(k,n) + 1.0_iwp
END DO
END DO
END IF
!-------------------------------------------------------------
! Add Diagonal coefficients
!-------------------------------------------------------------
DO m=1,Ndofs ! Loop over collocation points
Nod=0
DO n=1, Nodes
DO l=1,N_dof
IF (m == Ndest(n,l))THEN
Nod=n
EXIT
END IF
END DO
IF (Nod /= 0)EXIT
END DO
DO k=1,N_dof
DoF=Ndest(Nod,k)
IF(DoF /= 0) THEN
IF(NCode(DoF) == 1) THEN
Nel=0 ; Pos=0
DO i=1,Maxe
DO j=1,Ndofe
IF(DoF == Ldest(i,j))THEN
Nel=i ; Pos=j ; EXIT
END IF
END DO
IF(Nel /= 0)EXIT
END DO
F(m) = F(m) - Diag(m,k) * Elres_u(Nel,Pos)
ELSE
Lhs(m,DoF)= Lhs(m,DoF) + Diag(m,k)
END IF
END IF
END DO
END DO
!---------------------------------------------------------
! Solve system of equations iteratively
!---------------------------------------------------------
CALL bicgstab_l(Lhs,F,Ndofs,u1,0.0_iwp,tol,its,ell,kappa )