# Run atlas¶

This document will tell you how to start running atlas after you have done Download and Install. These instructions work best for the latest version.

## Get atlas running¶

Let’s say you compiled the software in a directory atlasofliegroups, or perhaps you put a pre-compiled binary there. Use your terminal to navigate into that directory. It should contain the executable files Fokko and atlas, and subdirectories “messages” (help files for Fokko) and “atlas-scripts” (auxiliary and help files for atlas).

Once you are there, depending on your setting, do either:

./atlas --path=atlas-scripts


or:

atlas --path=atlas-scripts


You should then see something like this:

This is 'atlas' (version 0.6, axis language version 0.9),
the Atlas of Lie Groups and Representations interpreter,
compiled on Jan 19 2016 at 02:21:55.   http://www.liegroups.org/
atlas>


Alternatively, you can cd into the atlas-scripts folder, then do:

../atlas


The folder atlas-scripts includes scripts, like “basics.at”, that define a collection of functions complementing the primitive functions built into atlas.

Assuming you are in the atlas environment (when you see atlas> in your terminal), here is how to load some scripts. For example, to load the file “basic.at” do:

atlas> <basic


You will see atlas output:

Starting to read from file 'atlas-scripts//basic.at'.
Added definition [12] of #: (int->[int])
Added definition [13] of #: (bool->int)
...


The symbol “<” means read a file. If this doesn’t work, please see Trouble Shooting. Also, there is a video explaining how to launch atlas so that it finds the necessary .at files.

Once this is working, you can and should load other files. Load “all.at” to get a recommended set of files:

atlas> <all
[... some atlas output ...]
atlas>


To check if readline (command completion, recalling previous commands, etc.) is working, hit TAB on your keyboard twice. You should see something like:

atlas>
Display all 902 possibilities? (y or n)


This indicates that command completion is working. Now do a few simple commands:

atlas> 1+1
Value: 2
atlas> set G=SL(2,R)
Identifier G: RealForm
atlas> print_block(trivial (G))
Parameter defines element 2 of the following block:
0:  0  [i1]  1   (2,*)  *(x=0,lam=rho+  [0], nu=  [0]/1)  e
1:  0  [i1]  0   (2,*)  *(x=1,lam=rho+  [0], nu=  [0]/1)  e
2:  1  [r1]  2   (0,1)  *(x=2,lam=rho+  [0], nu=  [1]/1)  1^e


Congratulations! Now you have atlas working on your machine! Proceed to Tutorial for some examples of what you can do with atlas.

## Quit atlas¶

Just type quit :)