作业帮关于matlab程序 PCA变换代码有些地方没看懂![M,N,bs] = size(multi);multi_mean = mean(mean(multi)); %多光谱影像各波段均值multi_Cx = 0; %协方差矩阵for i = 1 :Mfor j = 1 :Nmulti_S = multi(i,j,:);multi_S = multi_S - multi_mean;
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![关于matlab程序 PCA变换代码有些地方没看懂![M,N,bs] = size(multi);multi_mean = mean(mean(multi)); %多光谱影像各波段均值multi_Cx = 0; %协方差矩阵for i = 1 :Mfor j = 1 :Nmulti_S = multi(i,j,:);multi_S = multi_S - multi_mean;](/uploads/image/z/12579713-17-3.jpg?t=%E5%85%B3%E4%BA%8Ematlab%E7%A8%8B%E5%BA%8F+PCA%E5%8F%98%E6%8D%A2%E4%BB%A3%E7%A0%81%E6%9C%89%E4%BA%9B%E5%9C%B0%E6%96%B9%E6%B2%A1%E7%9C%8B%E6%87%82%21%5BM%2CN%2Cbs%5D+%3D+size%28multi%29%3Bmulti_mean+%3D+mean%28mean%28multi%29%29%3B+%25%E5%A4%9A%E5%85%89%E8%B0%B1%E5%BD%B1%E5%83%8F%E5%90%84%E6%B3%A2%E6%AE%B5%E5%9D%87%E5%80%BCmulti_Cx+%3D+0%3B+%25%E5%8D%8F%E6%96%B9%E5%B7%AE%E7%9F%A9%E9%98%B5for+i+%3D+1+%3AMfor+j+%3D+1+%3ANmulti_S+%3D+multi%28i%2Cj%2C%3A%29%3Bmulti_S+%3D+multi_S+-+multi_mean%3B)
关于matlab程序 PCA变换代码有些地方没看懂![M,N,bs] = size(multi);multi_mean = mean(mean(multi)); %多光谱影像各波段均值multi_Cx = 0; %协方差矩阵for i = 1 :Mfor j = 1 :Nmulti_S = multi(i,j,:);multi_S = multi_S - multi_mean;
关于matlab程序 PCA变换代码有些地方没看懂!
[M,N,bs] = size(multi);
multi_mean = mean(mean(multi)); %多光谱影像各波段均值
multi_Cx = 0; %协方差矩阵
for i = 1 :M
for j = 1 :N
multi_S = multi(i,j,:);
multi_S = multi_S - multi_mean;
multi_S = reshape(multi_S,bs,1); % 转换为bs行向量
multi_Cx = multi_Cx + multi_S * multi_S'; 这一步是求协方差的吗?
end
end
multi_Cx = multi_Cx / (bs - 1); 为什么要除以（bs-1）?
关于matlab程序 PCA变换代码有些地方没看懂![M,N,bs] = size(multi);multi_mean = mean(mean(multi)); %多光谱影像各波段均值multi_Cx = 0; %协方差矩阵for i = 1 :Mfor j = 1 :Nmulti_S = multi(i,j,:);multi_S = multi_S - multi_mean;
multi_Cx = multi_Cx + multi_S * multi_S' --------------- 这一步是求协方差的中间过程
multi_Cx = multi_Cx / (bs - 1);------------------------这个是协方差矩阵
