On Feb 22, 2010, at 10:37 , David MacMahon wrote:

> On Feb 22, 2010, at 6:42 , Andrew Ross wrote:
>
>> I would like to have a thorough comparison of the time difference.
>> This should include a "large data" case as well where timings  
>> might be
>> more important. The lena image might be one suitable case.
>
> As I said earlier, I share this concern.  My 100x test was done using
> the Lena image, but I agree that further analysis would be reassuring
> (or not as the case may be).

I have done some further performance testing using x20c (the test  
using the Lena image).  The results are slightly different, but still  
very encouraging.

I think my previous x20c loop tests were not a valid comparison  
because it turns out I was looping on a call to plimage, which I had  
not yet changed to call the plf2ops version named "plfimge".  I had  
created plfimagefr, but I had not created plfimage.  So I think my  
big x20c loop test was not really exercising new code.

I have since created plfimage (patch forthcoming) and modified x20c.c  
to loop 2000 times on each of the two calls to plimage that plot only  
Lena's eyes (one call plots only the eyes in their normal size/ 
position, the other call plots them "zoomed in").  This "subset"  
plotting involves copying parts of the 2D data array so it definitely  
makes use of the new plf2ops code.

I ran the modified x20c test three times using an unpatched libplplot  
with NO plf2ops stuff added and three times using a patched libplplot  
with the plf2ops stuff added.  Here are the results from my (now old)  
MacBook Pro laptop...

WithOUT plf2ops
---------------
2m 22.1s
2m 21.8s
2m 21.9s

WITH plf2ops
------------
2m 23.2s
2m 23.1s
2m 23.2s

So the plf2ops version took about 1.2 seconds longer than the non- 
plf2ops version or approximately a 1.5% performance hit.

It would be great is someone else could repeat this test and  
corroborate (or not) the results.

Dave


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