\partial_\theta causes infinite loop(?) in server

Question

As in my previous questions, I have

f::Depends(r,\theta,\phi, vr, vtheta, vphi);

The following works ok:

exfr:= { fr = \partial_r{f} };

but

exfth:= { fth = \partial_\theta{f} };

makes the server go into some kind of infinite loop (i.e., consumes ~ 99% CPU). So I have to restart the kernel.

Similarly,

exfvth:= { fvth = \partial_vtheta{f} };

causes infinite looping in server.

Enclosing the \theta or vtheta in braces works ok, i.e.,

exfth:= { fth = \partial_{\theta}{f} };

Answer 1

I guess you have your answer there: add braces. In general, Cadabra is less forgiving about not wrapping arguments in braces, so just do it always.

Cadabra should not hang of course, will investigate. I have opened an issue at https://github.com/kpeeters/cadabra2/issues/312.