[Tutor] Problems installing

Steven D'Aprano steve at pearwood.info
Wed Jun 30 12:18:02 CEST 2010

On Wed, 30 Jun 2010 03:35:10 pm Andrew Martin wrote:
> I just downloaded Python 2.6.5 onto my windows vista laptop. I am
> attempting to install "escript version 3: Solution of Partial
> Differential Equations (PDE) using Finite Elements (FEM)." I
> downloaded the files and manually placed them in their appropriately
> place on my computer according to the
> ReadMe file. However, when I try to import escript, I get an error:
> >>> import esys.escript
> Traceback (most recent call last):
>   File "<pyshell#0>", line 1, in <module>
>     import esys.escript
> ImportError: Bad magic number in
> C:\Python26\lib\site-packages\esys\escript\__init__.pyc

Is it possible that esys only provides compiled .pyc files, and that for 
a different version of Python?

If the .py file (source code) is there, Python *should* automatically 
delete the .pyc file (byte code) and re-compile it from the .py file. 
But if there is no .py file, then Python is stuck with using only the 
pre-compiled .pyc file, but it needs to have been compiled for the same 
version of Python. You can't have Python 2.6 run a .pyc file from 2.5 
or 3.1 (say). The "magic number" is there to declare the version of 
Python used.

Steven D'Aprano

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