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Avoid infinity calculations in rank_cd

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This commit is contained in:
Teodor Sigaev 2006-11-22 15:55:05 +00:00
parent ba2edcac4f
commit 84151d0644
1 changed files with 11 additions and 1 deletions
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12
contrib/tsearch2/rank.c
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@ -667,6 +667,7 @@ calc_rank_cd(float4 *arrdata, tsvector * txt, QUERYTYPE * query, int method)
{
double Cpos = 0.0;
double InvSum = 0.0;
int nNoise;
DocRepresentation *ptr = ext.begin;
while (ptr <= ext.end)
@ -676,7 +677,16 @@ calc_rank_cd(float4 *arrdata, tsvector * txt, QUERYTYPE * query, int method)
}
Cpos = ((double) (ext.end - ext.begin + 1)) / InvSum;
Wdoc += Cpos / ((double) ((1 + (ext.q - ext.p) - (ext.end - ext.begin))));
/*
* if doc are big enough then ext.q may be equal to ext.p
* due to limit of posional information. In this case we
* approximate number of noise word as half cover's
* length
*/
nNoise = (ext.q - ext.p) - (ext.end - ext.begin);
if ( nNoise < 0 )
nNoise = (ext.end - ext.begin) / 2;
Wdoc += Cpos / ((double) (1 + nNoise));
CurExtPos = ((double) (ext.q + ext.p)) / 2.0;
if (NExtent > 0 && CurExtPos > PrevExtPos /* prevent devision by