From: Andrew Jeffery <andrew@aj.id.au>
Date: Sat, 20 Feb 2016 10:52:41 +0000 (+1030)
Subject: strgrp: Add cosine fudge-curve to unify filter comparison spaces
X-Git-Url: https://git.ozlabs.org/?p=ccan;a=commitdiff_plain;h=e8f7a978bf4eb41c1877958e31a1a7213680335b;hp=e8f7a978bf4eb41c1877958e31a1a7213680335b

strgrp: Add cosine fudge-curve to unify filter comparison spaces

If we are to use should_grp_score_cos(x,y) as a filter the the following
relationship must hold (from least to most expensive):

        should_grp_score_len(x,y)
                >= should_grp_score_cos(x,y)
                >= grp_score(x)

should_grp_score_cos(x,y) wasn't holding up its part of the bargain, so
real data was used to generate a fudge curve to bring
should_grp_score_cos(x,y) results into the same space. Really this is a
terrible hack and the problem needs more thought. Evaluation of
should_grp_score_cos(x,y)'s performance benefit (given the relaxation of
the filter under the fudge curve) is sorely needed.
---