1 function [R,T,p,df] = dcor_uc(X,Y)
   2 % [R,T,p,df] = dcor_uc(X,Y)
   3 % Computes the U-centered (bias corrected) distance correlation between X and Y. Also outputs the
   4 % associated t-value (T) and p-value (p). Rows represent the examples, and columns the variables.
   5 
   6 % Based on: http://www.mathworks.com/matlabcentral/fileexchange/49968-dcorr--x--y--
   7 % and, the R package energy and papers by Szekely and Rizzo (2007; 2013 and 2014). 
   8 
   9 % Author: Linda Geerligs (lindageerligs@gmail.com), Date: 22-10-2015
  10 
  11 a = pdist2(X, X);
  12 b = pdist2(Y, Y);
  13 n=size(X,1);
  14 
  15 A = Ucenter(a,n);
  16 B = Ucenter(b,n);
  17 
  18 dcovXY = sum(sum(A.*B)) ./ (n*(n-3));
  19 dvarX = sum(sum(A.*A)) ./ (n*(n-3));
  20 dvarY = sum(sum(B.*B)) ./ (n*(n-3));
  21 
  22 R=dcovXY / sqrt(dvarX * dvarY);
  23 
  24 df=(n*(n-3))/2 -1;
  25 T=sqrt(df).*(R./sqrt(1-R.^2));
  26 p = tcdf(T,df,'upper');
  27 
  28 if R<0
  29     R=0;
  30 else
  31     R=sqrt(R);
  32 end
  33 
  34     function A = Ucenter(a,n)
  35         m = sum(a,2);
  36         M = sum(m)/((n - 1) * (n - 2));
  37         m = m./(n-2);
  38         A = a - repmat(m,[1 n]);
  39         A = A - repmat(m,[1 n])';
  40         A = A+M;
  41         A(eye(size(A))==1)=0;
  42     end
  43 
  44 end