Hello everyone I am having issues trying to solve a problem that has a matrix-vector product in its weak formulation. I defined a macro epsilon as follows : macro epsilon(u1, u2) [dx(u1), dy(u2), dy(u1)+dx(u2)] // and there is a term in the weak formulation that looks like this : int2d(Th)( …

Sadly, I don’t think it’s quite possible. However, you can trick the varf with a hand-defined macro. mesh Th; real[int, int] C(2,2); macro Cdense [[C(0,0), C(0,1)],[C(1,0), C(1,1)]]// varf vPb(u, v)= int2d(Th)( [2*v, v]'*Cdense*[3*u, u] );

Thank you for your reply, prj. Here I uploaded my problem using SNESSolve, all the macro and constants are deleted to reduce the program from 2300 lines to 270+ lines. This is a nonlinear problem F(x)=0, the F is given in funcRes part and the correct Jacobian matrix is obtained in funcJ part. Thei…

Your script doesn’t even run.

Sorry, I don’t have a simplified version that can run, sorry.

No, I mean that your script is wrong, I can’t even launch it on my machine.

Is the way of adding boundary condition in SNESSolve the same with TAO? If the initial value of boundary nodes are set to meet the requirements of boundary condition, can it be maintained using the constrain of upper and lower bound or using the form as on(1,2,3,4, du1=0,du2=0,du3=0) in varf functi…

Thans for your timely reply. I have found that in the definition of funcRes and funcJ, “tgv” is used in the vector and matrix forming such as “Loc = vPb(Wh, Wh, tgv = -2)” in SNESSolve. The tgv in FreeFem++ is always represent 1e30 to implement Dirichlet boundary conditions and in most situation c…

I always advise against using the default value of 10e+30. -1 (or -2 if your problem has homogeneous boundary conditions and is symmetric) is always better when you do iterative algorithms, such as a Newton loop in SNESSolve/TaoSolve.

Thanke you. I’m now using tgv=-2 in a SNESSolve iteration.

Dear prj Here I have uploaded a runable simplified version of my problem. This is a nonlinear problem F(x)=0, the F is given in funcRes part and the correct Jacobian matrix is obtained in funcJ part. Their forms have been proved in my original IPOPT program so don’t worry about that. The solution …

Matrix-vector multiplication in weak formulation

General Discussion

prj July 28, 2020, 7:10pm 27

The boundary conditions have to be set in your initial guess.

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Matrix-vector multiplication in weak formulation

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