Bug in split index cadabra 2.2.6 (build 2031.aa34dcb4e3 dated 2019-03-04)

Question

While using split index on an expression (named as 'ex' in the current case), the expression name C_aA repeats itself in the RHS with an equals sign.

https://drive.google.com/file/d/1_oIu_wTueFhukGCMCdoz0-ZGFwH3DqFo/view?usp=sharing

Is this a bug or is there information I'm missing?

Answer 1

There are some known issues with split_index on expressions which are not fully distributed; can you try distribute on your expression first?

Comments

Dear Kasper,

The error remains the same even after I distribute.

https://drive.google.com/file/d/1qTBHe_Hq0jVNZR7_r1kQv3tSRWlKwPpo/view?usp=sharing

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Oddly, this bug does not occur for some expression like the Kretschman scalar (self-contraction of the Riemann tensor).

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Can you send a (possibly minimal) notebook which reproduces this problem? It's difficult to guess what is going on based on that screenshot.

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Dear Kasper,

This bug seems to be occurring all the times I have something like

expr:= K_{a b ...} = "some expression"

If I simply put

expr:= "some expression",

the split index bug does not occur. However, if I need to use K_{a b ...} later in some other calculation, the latter method doesn't help.

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Dear Kasper,

Sample notebook

https://drive.google.com/file/d/17hG34HSWR0kKqfnh2fbjI7YRMYdg2eUt/view?usp=sharing

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Let me have a look.

Answer 2

I have pushed a fix for this to github master. Are you able to build from source?

Comments

I've built my current version from source. Do I update or rebuild it?

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git pull, and then run make and sudo make install again.

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Dear Kasper,

It works perfectly. Thanks a lot.

Best regards.

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Very good. Just for completeness: your notebook has a few weird things in it, e.g. Coordinate with a name as argument (it doesn't have one).

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So the subspace specification is redundant, I see. I was trying to break a spherically symmetric space into (t,r) and a 2-sphere. Does the Metric, InverseMetric, and KroneckerDelta take names as arguments or is it the same as Coordinate?

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They don't either. The manual pages are your friends (press F1 when your cursor is on a property name or algorithm name).