Thanks for the quick responses Erik and Miguel

To answer Erik's question, I intended to use Kranc as a simpler way to write the thorn and if the roadblocks didn't stop I was going to switch to manually writing the thorn using one of the hydrodynamic thorns as a skeleton framework to learn how to write a thorn for coupled equations, which is roughly where I was today if Kranc wasn't an easy fix. I will have to get back to you on your offer after I read through what Miguel has linked here thoroughly, but thank you for the offer.

Miguel, I believe I will need some time to take an in depth look at this before I can be sure that this is what I have been looking for, but I suspect it is exactly what I need, so thank you very much for this.

Nicholas Olsen

On Mon, Feb 7, 2022 at 1:51 PM Miguel Zilhão <mzilhao@ua.pt> wrote:

hi Nick,

i can't really help you out with Kranc, but we have a freely available thorn that does precisely the
Einstein-Klein-Gordon system. you can find it here as part of the Canuda library:
https://bitbucket.org/canuda/scalar/src/master/
i hope it helps.

cheers,
Miguel

On 07/02/2022 17:50, Nick Olsen wrote:
> Hello everyone
>
> I have been trying to write a thorn to couple the Klein-Gordon equations to the 3+1 Einstein
> equations. I can't figure out the details on how to make the thorn tell the ET how to update T_munu
> according to the evolution equations. I've been trying to write the thorn with Kranc without much
> luck, as Kranc isn't telling me anything when it does fail. I have attached the .m of the attempted
> thorn here. If anyone has any input or suggestions it would be greatly appreciated.
>
> Nicholas Olsen
>
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