Can't find the Invar database.

[PUSHPARAJ CHAKRAVARTI]

Hii all,

I am using Mathematica 12.1

The installation of xAct was totally fine. But I can't use the 'Invar' related operations. 

The Errors I get are-

<< xAct`Invar'

Get::noopen: Cannot open xAct`Invar.

In[23]:= gg[a, b] EOML2 // ContractMetric // RiemannToIn

Out[23]:= RInv::nodatabase: Can't find the Invar database. You can download it from http://www.xact.es/Invar/.

Please let me know why it is happening and how to make it work.

I have attached the notebook.

Cheers

Pushparaj

[Jose]

Hi,

First, note that you need

   <<xAct`Invar`

but you use

   <<xAct`Invar'

The final quote character is incorrect. You need backticks, grave accents. Not the standard single quote you have.

The Invar package comes with a database for small orders or Riemann polynomials. Then you need to download the rest of the database in a couple of compressed files of 40 and 250 MB, available here:

    http://xact.es/Invar/index.html

Perhaps you don't need the largest file (used for cases with 12 metric derivatives), but the smaller file (of 40 MB) is generally good to have.

Cheers,

Jose.