kernel bandwidths for imagenet dataset

dene - nxd matrix (very small subset of imagenet)

s=sum(dene,2);
ind=find(s>0);
dene=dene(ind,:);

aa=sum(dene.^2,2)*ones(1,size(dene,1));
bb=ones(size(dene,1),1)*sum(dene'.^2);
s2b=sqrt(aa+bb-2*dene*dene')./sqrt(aa+bb+2*dene*dene');

rbf=sqrt(aa+bb-2*dene*dene');
chi2 = vl_alldist(dene', dene', 'chi2') ;

1/mean(chi2(:)) = 0.1925
1/mean(rbf(:)) = 1.0693
1/mean(s2b(:)) = 1.8578

for BoW representation:
1/mean(chi2(:)) = 0.0011
1/mean(rbf(:)) = 0.013
1/mean(s2b(:)) = 1.25