[petsc-users] malloc error

[Jed Brown]

"Jorti, Zakariae via petsc-users" <petsc-users at mcs.anl.gov> writes:

> Hello,
>
>
> I am using TSSolve to solve a linear problem.
>
> In the FormIJacobian function that I provide to TSSetIJacobian, I first set the coefficients of both J and Jpre matrices the same way (J and Jpre matrices are equal in the first step). Then I call MatAXPY to prepare Jpre (Jpre := Jpre - another_matrix. So, Jpre and J are not equal anymore).

How do you call MatAXPY? What MatStructure arg are you passing? What is the sparsity pattern of another_matrix relative to Jpre?

>
> But I get the error once FormIJacobian is called the second time inside TSSolve:
>
> "[0]PETSC ERROR: New nonzero at (5,1) caused a malloc
>
> Use MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE) to turn off this check".
>
>
> It looks like MatAXPY changes the allocation of Jpre, which the second FormIJacobian does not like unless Jpre is destroyed first.
>
>
> Do you have any suggestions to fix this malloc issue?
>
> Thanks.
>
>
> Best regards,
>
>
> Zakariae