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<p class="MsoNormal"><span style="font-size:11.0pt">Jose,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Thanks for this. I will try this and report back.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Kenneth<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Jose E. Roman <jroman@dsic.upv.es><br>
<b>Date: </b>Friday, October 6, 2023 at 7:01 AM<br>
<b>To: </b>Kenneth C Hall <kenneth.c.hall@duke.edu><br>
<b>Cc: </b>petsc-users@mcs.anl.gov <petsc-users@mcs.anl.gov><br>
<b>Subject: </b>Re: [petsc-users] SLEPc/NEP for shell matrice T(lambda) and T'(lambda)<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:11.0pt">I am getting an error in a different place than you. I started to debug, but don't have much time at the moment.<br>
Can you try something? Comparing to ex21.c, I see that a difference that may be relevant is the MATOP_DUPLICATE operation. Can you try defining it for your A matrix?<br>
<br>
Note: If you plan to use the NLEIGS solver, there is no need to define the derivative T' so you can skip the call to NEPSetJacobian().<br>
<br>
Jose<br>
<br>
<br>
> El 6 oct 2023, a las 0:37, Kenneth C Hall <kenneth.c.hall@duke.edu> escribió:<br>
> <br>
> Hi all,<br>
> <br>
> I have a very large eigenvalue problem of the form T(\lambda).x = 0. The eigenvalues appear in a complicated way, and I must use a matrix-free approach to compute the products T.x and T’.x.<br>
> <br>
> I am trying to implement in SLEPc/NEP. To get started, I have defined a much smaller and simpler system of the form<br>
> A.x - \lambda x = 0 where A is a 10x10 matrix. This is of course a simple standard eigenvalue problem, but I am using it as a surrogate to understand how to use NEP.<br>
> <br>
> I have set the problem up using shell matrices (as that is my ultimate goal). The full code is attached, but here is a smaller snippet of code:<br>
> <br>
> !.... Create matrix-free operators for A and B<br>
> PetscCall(MatCreateShell(PETSC_COMM_SELF,n,n,PETSC_DETERMINE,PETSC_DETERMINE, PETSC_NULL_INTEGER, A, ierr))<br>
> PetscCall(MatCreateShell(PETSC_COMM_SELF,n,n,PETSC_DETERMINE,PETSC_DETERMINE, PETSC_NULL_INTEGER, B, ierr))<br>
> PetscCall(MatShellSetOperation(A, MATOP_MULT, MatMult_A, ierr))<br>
> PetscCall(MatShellSetOperation(B, MATOP_MULT, MatMult_B, ierr))<br>
> <br>
> !.... Create nonlinear eigensolver<br>
> PetscCall(NEPCreate(PETSC_COMM_SELF, nep, ierr))<br>
> <br>
> !.... Set the problem type<br>
> PetscCall(NEPSetProblemType(nep, NEP_GENERAL, ierr))<br>
> !<br>
> !.... set the solver type<br>
> PetscCall(NEPSetType(nep, NEPNLEIGS, ierr))<br>
> !<br>
> !.... Set functions and Jacobians for NEP<br>
> PetscCall(NEPSetFunction(nep, A, A, MyNEPFunction, PETSC_NULL_INTEGER, ierr))<br>
> PetscCall(NEPSetJacobian(nep, B, MyNEPJacobian, PETSC_NULL_INTEGER, ierr))<br>
> <br>
> The code runs, calls MyNEPFunction and MatMult_A multiple times, sweeping over the prescribed RG range, but crashes before it ever calls MyNEPJacobian or MatMult_B. The NEP viewer and error messages are attached.<br>
> <br>
> Any help on getting this problem properly set up would be greatly appreciated.<br>
> <br>
> Kenneth Hall<br>
> ATTACHMENTS: <br>
> test_nep.f90<br>
> code_output<br>
> <br>
> <code_output><test_nep.f90><o:p></o:p></span></p>
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