Re: tsearch2 questions

On 7/4/07, Joshua N Pritikin <jpritikin(at)pobox(dot)com> wrote:
>
> From where are you quoting? I was quoting from:
>
> http://www.sai.msu.su/~megera/postgres/gist/tsearch/V2/docs/tsearch2-ref.html

i was quoting file
http://www.sai.msu.su/~megera/postgres/gist/tsearch/V2/docs/tsearch-V2-intro.html
or actually - it's copy provided with sources of postgresql in
contrib/tsearch2/docs directory.

> actually oleg supposed not to use best rank, but just use the formula as
> > given - rank/(rank+1) to get rank in range of 0 to 1.
> OK, then what does the +1 mean in your formulae? Consider these results
> from [1]. rank/(rank+1): 0.19/.1 = 1.9, .1/.1 = 1, etc. That doesn't
> make sense. The reciprocal also doesn't make sense. So what does Oleg
> mean? I was guessing that Oleg meant to divide the rank column by the
> first rank, that is, by 0.19 so you would get 1, .52, .52, etc.
>

+1 means: add one to.
for example: for rank = 0.1 you get: 0.1/(0.1+1) = 0.1/1.1 = 0.0909
for rank = 0.5 you get: 0.5/(0.5+1) = 0.5/1.5 = 0.3333

i think that notation: rank+1 is pretty readable.

additionally - sorry but i dont understand your calculations. what is 0.19/.1
? how did you get the .1?

depesz