[Numpy-discussion] Speeding up Numeric

Fernando Perez Fernando.Perez at colorado.edu
Sat Jan 22 00:36:45 CST 2005

konrad.hinsen at laposte.net wrote:
> On 21.01.2005, at 22:40, Paul F. Dubois wrote:
>>As I mentioned in a recent post, the original Numeric philosphy was 
>>damn the torpedos full steam ahead; performance first, safety second. 
>>There was a deliberate decision not to handle NaN, inf, or anything 
>>like it, and if you overflowed you should die.
> There was also at some time the idea of having a "safe" version of the 
> code (added checks as a compile-time option) and an installer that 
> compiled both with different module names such that one could 
> ultimately choose at run time which one to use. I really liked that 
> idea, but it never got implemented (there was a "safe" version of ufunc 
> in some versions but it was no different from the standard one).

I really like this approach.  The Blitz++ library offers something similar: if 
you build your code with -DBZ_DEBUG, it activates a ton of safety checks which 
are normally off.  The performance plummets, but it can save you days of 
debugging, since most pointer/memory errors are flagged instantly where they 
occur, instead of causing the usual inscrutable segfaults.

F2PY also has the debug_capi flag which provides similar services, and I've 
found it to be tremendously useful on a few occasions.

It would be great to be able to simply use:

#import Numeric
import Numeric_safe as Numeric

to have a safe, debug-enabled version active.  The availability of such a 
version would also free the developers from having to cater too much to safety 
considerations in the default version.  The default could be advertised as 
'fast car, no brakes, learn to jump out before going off a cliff', with the 
_debug 'family minivan' being there if safety were needed.



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