[Yt-dev] sigma

[Matthew Turk]

Okay, sounds good.  I'll add it in tonight or tomorrow.

On Wed, Feb 4, 2009 at 1:35 PM, david collins <antpuncher at gmail.com> wrote:
>> Well, nuts.  Okay, I'll take a look at this later today or tomorrow.
>> Maybe we should make a special "calculate error" function?
>
> Meh.  I vote do the simple way, and if it looks like the person-hours
> in savings to increase the speed are worth the person-hours cost in
> figuring out a faster way (keeping in mind that two of us are trying
> to graduate) then do it.  It's at *best* a factor of 2 in cost for
> something that's been pretty quick for me, so I don't see it as worth
> your time to speed it up.  It's not an increase of accuracy to do sum(
> w_i * ( v_i - M )^2) / sum(w_i), I don't think, since you do the
> difference in the square.
>
> d.
>
>>
>> On Wed, Feb 4, 2009 at 12:47 PM, david collins <antpuncher at gmail.com> wrote:
>>> I vote do it the 2 pass way.  I've been looking at this this morning,
>>> and what I keep coming up with (though I don't have a full solution)
>>> is that you're going to need to compute partial sums of the weight
>>> field.  I think this pass through the weight field almost outweighs
>>> the advantage of using this single pass approach.
>>>
>>> d.
>>>
>>> On Wed, Feb 4, 2009 at 10:23 AM, david collins <antpuncher at gmail.com> wrote:
>>>>> so we'll need to weight the values to calculate std-dev, yes?
>>>>
>>>> I think I answered the wrong question.  Ignore my first post, the UT
>>>> matrix is irrelevant.
>>>>
>>>> d.
>>>>
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