[SciPy-dev] Absoft & Scipy

Pearu Peterson pearu at scipy.org
Thu Feb 3 13:58:57 CST 2005

On Thu, 3 Feb 2005, Stephen Walton wrote:

> Pearu Peterson wrote:
>> Check Absoft compiler
>> manual if it provides options that forces external names to be appended 
>> with exactly *one* underscore, and try to modify 
>> scipy_distutils/absoftfcompiler.py accordingly.
> Sigh.  I found the problem but am not sure of a workaround.  I've created an 
> /opt/absoft/default.opt file locally which forces Absoft to use the '-g77' 
> switch on all compiles for maximum compatibility with binaries from that 
> compiler.   This means that it does the double underscore append.  Without 
> -g77 and with -YEXT_SFX=_ on the Absoft command line, one gets a single 
> underscore as desired.  With both, one gets three underscores!
> From my point of view, the simplest solution would be for f2py to respect 
> g77's defaults rather than override them, even though in this case I agree 
> g77's default is stupid.  But there's a better reason than personal 
> preference:  If I install fftw from the Fedora RPMs, they were compiled with 
> g77 and therefore have the double underscores on external names with embedded 
> underscores.  I need to minimize the time I spend doing admin tasks (see my 
> recent conversation with Fernando) and would rather not have to add fftw to 
> the list of things I have to compile myself with special switches to keep 
> scipy working.

Right now I don't have a solution to this chicken&egg problem: using 
'-g77' in /opt/absoft/default.opt is upto a sysadmin or whoever maintains
absoft compiler installation while f2py has used for a long time 
the exactly-single underscore convention in order to support also other 
compilers than g77. And if '-g77' would not be used in 
/opt/absoft/default.opt, scipy should build fine with this convention.
I am not sure which party of absoft compiler users is larger, those who 
use -g77 or those who do not.

Anyway, recent f2py from CVS supports now -DUNDERSCORE_G77 that will cause 
extra underscore appended to those names that contain an underscore.
So, to build scipy with the absoft fortran compiler that uses -g77 by 
default, get f2py from CVS, install it, and use the following command

   python setup.py build_ext -DUNDERSCORE_G77 build

Note that if any of the fortran libraries used by scipy is not compiled
with -g77, you have the same problem but inversed. Then one should not
use -DUNDERSCORE_G77. Right now scipy_distutils/system_info.py cannot
test this automatically.


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