There isn’t any documentation for installing Cantera on Mac OS X, and although it should be straight forward I encountered some problems and I want to try to fill that documentation void. Cantera is incredibly powerful software and the creator (Dave Goodwin) is helpful and active on the official newsgroup.

My Settings

My system specifications are:
* Mac OS X 10.4.2
* XCode 2.0 developer tools (current version as of 9/13/05)
* Matlab 7 (R14)
* Cantera installed using the 1.6.0 binary release from [http://sourceforge.net/projects/cantera/ Sourceforge] in the files section.

The Symptoms

I could not run the Cantera examples from Python or Matlab and was encountering the following types of errors:

>> run_examples
EQUIL a chemical equilibrium example.

Error in ==> run_examples at 3
equil(0);
and from within Python

-----:/Applications/Cantera/demos/python/flames -----$ python flame1.py
Traceback (most recent call last):
File "flame1.py", line 7, in ?
from Cantera import *
ImportError: No module named Cantera

The Fix

The error messages indicate that Python is not aware of the Cantera module. After some thought and googling I decided that I should check what directories Python is searching for its modules. The PYTHONPATH environment variable can be printed by importing sys and printing sys.path.

-----:/Applications/Cantera/demos/python/flames -----$ python
Python 2.3.5 (#1, Mar 20 2005, 20:38:20)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1809)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print sys.path
['', '/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python23.zip',
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3',
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/plat-darwin',
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/plat-mac',
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/plat-mac/lib-scriptpackages',
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/lib-tk',
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/lib-dynload',
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/site-packages',
'/System/Library/Frameworks/Python.framework/Versions/2.3/Extras/lib/python']

As you can see above, the /Libary/Python/2.3/ (or, optionally I think, the /Applications/Cantera/bin/) directory are not being searched for modules, and it happens that the Cantera files are located in those directories. In order to search additional directories you can create .pth files in the current search path to add additional directories to the search path. There is a file called Extras.pth in the /Library/Python/2.3/site-packages/ directory which will do just this task and it’s a simple task to add our new directories.

Open the Extras.pth file from the command line:
emacs /Library/Python/2.3/site-packages/Extras.pth
Edit it so that it looks like this:

/System/Library/Frameworks/Python.framework/Versions/2.3/Extras/lib/python
/Library/Python/2.3/
And then save and close it with Control-X Control-S and Control-X Control-C