Re: [Numpy-discussion] rcond in polyfit

[Tim H. <tim...@ie...>]

Charles R Harris wrote:
>
>
> On 10/14/06, *A. M. Archibald* <per...@gm... 
> <mailto:per...@gm...>> wrote:
[SNIP]
>
>
> Hmmm, I wonder if we have a dictionary of precisions indexed by dtype 
> somewhere?

Here's some code I stole from somewhere for computing EPS. It would easy 
enough to generate the dictionary you are looking for at startup using 
this. I can't recall the pedigree of this code though, so caveat emptor:

    def bits_of_precision(dtype):
        one = np.array([1], dtype)
        i = 0
        while not np.alltrue(one + (one / 2.**i) == one):
            i += 1
        return i - 1
       
       
    EPSS = 1.0  / 2**bits_of_precision(float) * 10 # XXX safety factor


It's sorta old and translated from numpy too, so it could probably be 
rewritten in better style.

-tim


>  
[SNIP]