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Re: svn commit: r332747 - in /lucene/java/trunk: ./ src/java/org/apache/

Subject: Re: svn commit: r332747 - in /lucene/java/trunk: ./ src/java/org/apache/lucene/search/regex/ src/test/org/apache/lucene/search/regex/
From: Yonik Seeley
Date: Thu, 17 Nov 2005 16:10:09 -0500
> The float epsilon should ideally be greater than the minimum score
> increment,

I'm not sure I understand why this is.  epsilon is based on 1,
(smallest number such that 1-epsilon != 1, right?).  What's special
about 1?

I'm worried about the impact of things like this:
 smallfloat(10) + smallfloat(1) + smallfloat(1) + smallfloat(1) -> 10

And it makes things very order dependent:
 smallfloat(1) + smallfloat(1) + smallfloat(1) + smallfloat(10) -> 12

Also, epsilon related to the mantissa, not the exponent?
That would make it 1/8, not 1/32.

Also, if we don't need to represent very small numbers, we could lower
the zero point of the exponent (currently it's 15 for the 5/3 split),
right?

For reference, here are some of the current byte->float mappings around 1:
116) 0.25
117) 0.3125
118) 0.375
119) 0.4375
120) 0.5
121) 0.625
122) 0.75
123) 0.875
124) 1.0
125) 1.25
126) 1.5
127) 1.75
128) 2.0
129) 2.5
130) 3.0
131) 3.5
132) 4.0
133) 5.0
134) 6.0
135) 7.0
136) 8.0
137) 10.0
138) 12.0
139) 14.0
140) 16.0
141) 20.0
142) 24.0
143) 28.0
144) 32.0
145) 40.0
146) 48.0
147) 56.0
148) 64.0
149) 80.0
150) 96.0
151) 112.0
152) 128.0


-Yonik
Now hiring -- http://forms.cnet.com/slink?231706

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