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CONST
Small = 0.000001;
VAR
i,j : INTEGER;
AA : StateMatrix;
BB,Ax : StateVector;
rsq : REAL;
(*$I mtt_solve.p *)
(*$I mtt_sparse.p *)
BEGIN{mtt_update}
IF Method=1 THEN {Euler}
FOR i := 1 TO Nx DO
xnew[i] := xnew[i] + dx[i]*DT
ELSE IF (Method=2) OR (METHOD=3) THEN {Implicit}
BEGIN
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FOR i := 1 TO Nx DO
BB[i] := x[i] + DT*(dx[i]-Ax[i]);
{Solve the equation AAx = B}
mtt_solve(xnew,AA,BB,Nx,Small);
END
ELSE IF (METHOD=4) THEN {Sparse CG implicit}
BEGIN
mtt_asub(x,Ax,Nx); {Sparse computation of (1-A*dt)*x}
FOR i := 1 TO Nx DO
BB[i] := Ax[i]+ DT*dx[i];
mtt_sparse(BB,Nx,xnew,rsq); {Sparse CG solution
- using prev. xnew as starter}
END
ELSE
Writeln("Method >2 is not defined");
ELSE
Writeln("Method >4 is not defined");
END{mtt_update};
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