//function HC=hist_cost_2(BH1,BH2);
//% HC=hist_cost_2(BH1,BH2);
//%
//% same as hist_cost.m but BH1 and BH2 can be of different lengths
public Matrix HistCost(Matrix BH1, Matrix BH2)
{
if (BH1.Columns != BH2.Columns)
throw new Exception("槽数不等没法比！");
//[nsamp1,nbins]=size(BH1);
//[nsamp2,nbins]=size(BH2);
int nbins = BH1.Columns;
//BH1n=BH1./repmat(sum(BH1,2)+eps,[1 nbins]);
//%应该是repmat的结果 [sum(BH1,2),sum(BH1,2),sum(BH1,2),sum(BH1,2),sum(BH1,2).....]
var BH1n = BH1.PointDivide((BH1.Sum2() + Epsilons(nsamp1, 1)).RepMat(1, nbins));
//BH2n=BH2./repmat(sum(BH2,2)+eps,[1 nbins]);
var BH2n = BH2.PointDivide((BH2.Sum2() + Epsilons(nsamp2, 1)).RepMat(1, nbins));
//tmp1=repmat(permute(BH1n,[1 3 2]),[1 nsamp2 1]); % permute似乎用来改变维的顺序
//tmp2=repmat(permute(BH2n',[3 2 1]),[nsamp1 1 1]);
//HC=0.5*sum(((tmp1-tmp2).^2)./(tmp1+tmp2+eps),3);
// 不知道怎么弄，猜吧
DenseMatrix cost = Zeros(BH1.Rows, BH2.Rows);
for (int i = 0; i < BH1.Rows; ++i) { // BH1的每一行
var BH1nrow = BH1n.GetRow(i);
for (int j = 0; j < BH2.Rows; ++j) { // BH2的每一行
var BH2nrow = BH2n.GetRow(j);
double costij = 0;
for (int k = 0; k < nbins; ++k) {
//double tmp1 = BH1n[i, k], tmp2 = BH2n[j, k];
double tmp1 = BH1nrow[k], tmp2 = BH2nrow[k];
costij += ((tmp1 - tmp2) * (tmp1 - tmp2)) / (tmp1 + tmp2 + Epsilon);
}
cost[i, j] = costij * 0.5;
}
}
return cost;
}