On 28 October 2011 08:45, Robert Layton <[email protected]> wrote:
> On 27 October 2011 23:22, Satrajit Ghosh <[email protected]> wrote:
>
>> hi robert,
>>
>>
>>> I had a way of doing it that would be really robust, but really slow.
>>> Expand each of the factorials on the denominator and numerator separately
>>> and store as separate lists. Then remove all terms common to both lists and
>>> multiply the results. However, this heavily uses append and would be too
>>> slow for large value of N.
>>>
>>
>> another exact solution would be to do an accumulator trick (treating
>> every factorial as a factor):
>>
>> def run_accumulate(all_factors):
>> a = np.zeros((all_factors.max()+1))
>> b = np.arange(all_factors.max()+1)
>> for factor in all_factors:
>> a[:(abs(factor)+1)] += np.sign(factor)
>> return np.exp(np.dot(a[2:], np.log(b[2:])))
>>
>> seems to run pretty quickly
>>
>> %timeit run_accumulate(np.array([50, 10, -30, -20])) # numerator factors
>> are +ve, denominator is -ve
>>
>> 10000 loops, best of 3: 98.3 us per loop
>>
>> cheers,
>>
>> satra
>>
>>
>>
>> ------------------------------------------------------------------------------
>> The demand for IT networking professionals continues to grow, and the
>> demand for specialized networking skills is growing even more rapidly.
>> Take a complimentary Learning@Cisco Self-Assessment and learn
>> about Cisco certifications, training, and career opportunities.
>> http://p.sf.net/sfu/cisco-dev2dev
>> _______________________________________________
>> Scikit-learn-general mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/scikit-learn-general
>>
>>
> I haven't seen this pattern before - that should probably work well.
> I'll have some time this weekend, so I think I'll be implementing three
> different versions!
>
> - Robert
>
>
I tried all of these suggestions, and could not get any to work.
Anyone have some ideas? I've pushed my current code to this PR, have a look
at let me know.
Thanks,
Robert
--
My public key can be found at: http://pgp.mit.edu/
Search for this email address and select the key from "2011-08-19" (key id:
54BA8735)
Older keys can be used, but please inform me beforehand (and update when
possible!)
------------------------------------------------------------------------------
RSA(R) Conference 2012
Save $700 by Nov 18
Register now
http://p.sf.net/sfu/rsa-sfdev2dev1
_______________________________________________
Scikit-learn-general mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/scikit-learn-general
