[SciPy-user] small error problem

Travis Oliphant oliphant at ee.byu.edu
Sun Oct 30 01:40:57 CDT 2005


Ryan Krauss wrote:

>Interesting.  I was starting ipython with -p scipy.
>
>If I enter
>scipy.restore_numeric()
>
>I get
>(Pdb) mat[1,1]/mat[1,0]-mat[0,1]/mat[0,0]
>Out[4]: -3.5527136788005009e-15
>both before and after I augment the column of zeros (instead of
>exactly 0.0 before augmenting and -1.303556573795106e-08 after
>aygmenting if I don't restore numeric).
>  
>
This sounds reasonable.  An answer of 0.0 was just how it was being 
printed (you'd have to look at the bit pattern to know for sure). 

So, it definitely looks like some precision issue with different types 
in the old alter numeric.  As the approach is obsolete, that problem is 
going to have to just sit there for a while.

-Travis



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