Weeds has been distributed with GILDAS since March 2010. Provided that you have installed GILDAS with the Python extension (named PyGILDAS)1you should have Weeds already installed on your computer. If this is not the case, please refer to the GILDAS documentation for instructions on how to install PyGILDAS.
Let us first start CLASS from a terminal:
[fontsize=\scriptsize] % class GILDAS Version: dev (18mar14 12:00) (x86_64-darwin-gfortran) executable tree * Welcome to CLASS * Loaded modules atm sic (J.Pety, S.Bardeau, S.Guilloteau, E.Reynier) greg (J.Pety, S.Bardeau, S.Guilloteau, E.Reynier) ephem (F.Gueth, J.Pety) class (S.Bardeau, J.Pety, P.Hily-Blant, S.Guilloteau) * Loaded extensions weeds (S.Maret, P.Hily-Blant, J.Pety, S.Bardeau, E.Reynier) (...) LAS>
Note that the welcome message mentions that the Weeds extension as
been loaded. The extension defines a language, named
weeds\. This language has a number of commands, the list of
which can be obtained by typing:
[fontsize=\scriptsize] LAS90> help weeds\ Weeds is a CLASS extension to analyze spectral surveys or spectral lines observations with large bandwidths. It provides several commands to identify lines on a spectrum and to model it. Available commands: LID Identify lines on the current spectra LFIND Find lines from a species within a frequency range LLIST List lines from the line index LGET Get a line from the line index LPLOT Plot a line from the current line index MODSOURCE Model the emission of a source at the LTE MODSHOW Show the results of MODSOURCE For more information of each command, type 'help <command>'
Each of the commands provided by Weeds has an extensive
help followed by the command name to read