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Added fabs() to variance, which can sometime be negative in case 

of rounding errors (and sqrt chokes on it).
This commit is contained in:
Federico Ponchio 2005-06-07 09:37:33 +00:00
parent 17fb55c9e0
commit 6c1fdb3066
1 changed files with 8 additions and 3 deletions
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11
vcg/math/histogram.h
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@ -24,6 +24,9 @@
History
$Log: not supported by cvs2svn $
Revision 1.5 2005/06/07 07:44:08 cignoni
Added Percentile and removed small bug in Add
Revision 1.4 2005/04/04 10:48:35 cignoni
Added missing functions Avg, rms etc, now fully (almost) functional
@ -68,7 +71,7 @@ public:
ScalarType Percentile(ScalarType frac) const;
ScalarType Avg() { return avg/cnt; }
ScalarType RMS() { return sqrt(rms/double(cnt));}
ScalarType Variance() { return rms/cnt-Avg()*Avg(); }
ScalarType Variance() { return fabs(rms/cnt-Avg()*Avg()); }
ScalarType StandardDeviation() { return sqrt(Variance()); }
void FileWrite(const std::string &filename);
@ -149,8 +152,10 @@ ScalarType Histogram<ScalarType>::Percentile(ScalarType frac) const
assert(frac>=0 && frac<=1);
ScalarType sum=0,partsum=0;
int isum=0,ipartsum=0;
for(int i=0;i<n+1;i++) { sum+=H[i]; isum+=H[i];}
assert(isum==cnt);
int i;
for(i=0;i<n+1;i++) { sum+=H[i]; isum+=H[i];}
assert(isum==cnt);
assert(sum==cnt);
sum*=frac;