TS

[Manav Bhatia]

Hi

     I am preparing my code to use the TS capability of Petsc, and I  
had a few doubts to clear up. These primarily relate to the set up of  
the problem, and I have stated them below. Please correct me if I am  
wrong.

-- For a linear transient problem, I understand that the following  
different combinations are possible:
1>  A(t) U_t = f (t)
        where I will have to call the setLHSMatrix() and setRHSFunction()  
functions during set up.
2> A(t) U_t = B(t) U
        where I will have to call the setLHSMatrix() and setRHSMatrix()  
functions during set up.
3> U_t = f(t)
        where I call only the setRHSfunction()
4> U_t = A(t) U
        where I call only the setRHSMatrix()


-- For a nonlinear transient problem, I understand that the following  
different combinations are possible:
1>  A(t) U_t = f (U, t)
        where I will have to call the setLHSMatrix() and setRHSFunction(),  
and setRHSJacobian() functions during set up.
2> U_t = f(U, t)
        where I will have to call the setRHSfunction() and setRHSJacobian()  
functions during set up.


-- setting KSP and PC types
   From what I understand, I can set up the KSP and PC type of the  
transient solver, which will be used only if I specify an A matrix  
for the problem. In addition, I can independently set the KSP and PC  
type of the SNES used by TS, which is used by the time solver.


Kindly help me with your advice here.

Thanks,
Manav