# eliminate_kronecker(_) crashes on double derivatives

+1 vote

Hi,

It seems that the algorithm eliminate_kronecker(_); crashes when acting on double derivatives. (I'm running Cadabra on Mac OS High Sierra v 10.13.6. )

For example, the following program does not compile:

{A,B,C,D,E,F,G,I,K,L,M,N,Q,R,S,T,U#}::Indices(double, position=fixed);

\partial{#}::PartialDerivative;

g_{A B}::KroneckerDelta;

Exp:= g_{A B}*\partial_{A B}{d};

eliminate_kronecker(_);

Thank you for any help!

+1 vote

When I run this, it correctly tells me that there is a repeated upper or lower index of fixed type (so there is an error message, but not a crash). If you want this to work with the index positions as they stand, you need to declare the index type as position=free. Fixed type indices of a given name can only occur once in super or subscript position.

by (66.3k points)

Thank you! Indeed, it works now. As for the error message, I can't see any while using the gtk interface. Rather, when there is an error (as in this case), nothing shows up and the loading symbol (at the bottom of the page) keeps running in circle forever. Is there a way to circumvent this problem so that to get these error messages? Thank you already for any information.

On which platform are you running Cadabra (Linux/macOS/Windows)? And which version? And how did you install it (build from source or use a binary installer)?

I am using Mac OS High Sierra v 10.13.6. I built it from source using Homebrew. About the version, I built around June 2018.

I'm not sure whether it is related or not but when executing cadabra2-gtk, the following error message displays in the terminal:

(process:2742): Gtk-WARNING **: 15:31:41.841: Locale not supported by C library. Using the fallback 'C' locale.

Ok, let me try to reproduce the problem, I'll get back to you. The Gtk-WARNING has nothing to do with it, in any case.

I can indeed reproduce that here. Will try to have a look at the problem later tonight.

Great, thanks a lot!

I have pushed some changes to github which (at least on my mac) make error messages appear again. Can you give it a shot?

Yes, I can see error messages now! Thank you very much!