源域：
2.1789	1.7811	5.079	4.9312
0.8621	2.1287	4.9825	2.3388
2.6347	1.9563	4.5392	4.8442
2.7179	2.9001	4.9027	4.8582
2.6686	1.6799	4.3792	4.6411
1.6736	2.3081	4.8384	3.2979
1.5666	2.6467	5.0504	4.459
-0.5611	2.2365	4.3925	5.1316
5.6693	1.7355	4.5335	4.6407
3.2032	2.103	4.1948	5.2605
3.3525	2.8301	4.6383	5.6972
-1.0407	3.5198	4.7106	4.9243
3.9229	2.1161	4.5666	1.772
2.5607	3.802	4.2681	4.6322
3.3072	2.5083	4.6095	2.2236
2.7121	2.4338	4.136	2.2348
5.3547	2.1088	4.402	4.9884
1.8302	1.4921	4.6216	3.5862
2.8891	2.1286	4.6419	3.8606
-0.0896	2.6894	3.6843	6.6392
3.1404	1.9461	4.2604	5.9859
2.3406	3.1988	5.0872	4.7518
2.5067	2.9704	4.2749	4.3441
8.2153	1.7592	5.2409	3.8201
0.3027	2.7589	3.9826	4.8484
4.0223	1.7566	4.6219	4.92
6.1367	2.1098	4.7832	5.4567
4.9795	2.418	4.7726	3.1959
-1.0746	2.4311	4.7683	4.5599
5.4939	2.6046	4.4663	5.1159
4.5709	1.9838	4.9596	4.9317
1.3746	2.6845	5.1921	3.2068
1.7178	0.7976	4.6948	3.7012
目标域：
1.9584	2.0242	4.7594	2.587
-2.8342	3.4594	4.4371	5.2375
1.6251	2.7737	5.0145	6.3262
0.7016	2.5265	4.8881	3.2105
3.5579	2.5773	4.856	4.283
4.3282	2.7581	4.7095	6.715
3.1619	2.5427	4.1323	5.5883
4.9933	2.2985	3.8455	3.8381
3.2214	2.6478	4.3276	2.5246
-0.2848	2.5853	4.6481	3.4857
2.876	1.5096	3.9921	2.4505
0.8559	2.5633	5.483	3.0589
4.2149	2.6618	4.2017	3.3713

function mmd_XY=my_mmd(X, Y, sigma)
%Author：kailugaji
%Maximum Mean Discrepancy 最大均值差异 越小说明X与Y越相似
%X与Y数据维度必须一致, X, Y为无标签数据，源域数据，目标域数据
%mmd_XY=my_mmd(X, Y, 4)
%sigma is kernel size, 高斯核的sigma
[N_X, ~]=size(X);
[N_Y, ~]=size(Y);
K = rbf_dot(X,X,sigma); %N_X*N_X
L = rbf_dot(Y,Y,sigma);  %N_Y*N_Y
KL = rbf_dot(X,Y,sigma);  %N_X*N_Y
c_K=1/(N_X^2);
c_L=1/(N_Y^2);
c_KL=2/(N_X*N_Y);
mmd_XY=sum(sum(c_K.*K))+sum(sum(c_L.*L))-sum(sum(c_KL.*KL));
mmd_XY=sqrt(mmd_XY);

function H=rbf_dot(X,Y,deg)
%Author：kailugaji
%高斯核函数/径向基函数 K(x, y)=exp(-d^2/sigma), d=(x-y)^2, 假设X与Y维度一样
%Deg is kernel size,高斯核的sigma
[N_X,~]=size(X);
[N_Y,~]=size(Y);
G = sum((X.*X),2);
H = sum((Y.*Y),2);
Q = repmat(G,1,N_Y(1));
R = repmat(H',N_X(1),1);
H = Q + R - 2*X*Y';
H=exp(-H/2/deg^2);  %N_X*N_Y

>> mmd_XY=my_mmd(x, y, 4)

mmd_XY =

    0.1230