[petsc-users] Any workarounds for TAO in a complex scalar type code?

[Junchao Zhang]

On Thu, Jun 24, 2021 at 3:25 PM Dener, Alp via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Hi Lucas,
>
> In theory, you can attempt to solve complex-valued problems by
> concatenating the real and imaginary parts into a single real-valued
> solution vector and solving it as if it’s a real-valued problem.
>
> There’s a more practical issue of the PETSc build excluding the TAO source
> code entirely for complex builds. I think this is done because we cannot
> guarantee that TAO code has been completely rigorous in its distinction of
> PetscReal from PetscScalar. There may be places where we used Scalar and
> assumed it’s Real. The methods developed in the last few years have paid
> more attention to this but there’s a lot of older code floating around that
> might break even if you hacked the build into compiling TAO for complex
> configurations.
>
If an expression does not support PetscComplex, shouldn't it report a
compilation error?

>
> I’m not entirely sure what’s necessary to enable TAO builds for complex
> PETSc. Perhaps Todd, Satish or Barry will have a better idea. If you want
> to give it a try though I’d be happy to help you resolve the errors as they
> come up so that it can be compiled for complex builds. Can’t provide
> convergence guarantees but it would at least let you attempt a solution.
>
> Alp
>
> On Jun 24, 2021, at 2:44 PM, Lucas Banting <bantingl at myumanitoba.ca>
> wrote:
>
> Hi,
>
> I have a complex valued optimization code that requires non-linear least
> squares curve fitting at each iteration. I wanted to use Tao to do the
> non-linear least squares problem, but just discovered that Tao can only be
> used with real scalar types. Is there any workarounds?
>
> I was wondering if maybe I could somehow use two different Petsc
> installations at once, or is there any other ways to hack tao into working?
>
> Thanks,
> Lucas
>
>
>
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