Matlab realization on covariance matrix

Mysample=fix(rand(10,3)*50)

Mysample =

40     7    32
45    48     1
 6    47    42
45    24    46
31    40    33
 4     7    37
13    21    37
27    45    19
47    39    32
48    47     8

dim1=Mysample(:,1); dim2=Mysample(:,2); dim3=Mysample(:,3); cov12=sum((dim1-mean(dim1)).(dim2-mean(dim2)))/(size(Mysample,1)-1); cov13=sum((dim1-mean(dim1)).(dim3-mean(dim3)))/(size(Mysample,1)-1); cov23=sum((dim2-mean(dim2)).*(dim3-mean(dim3)))/(size(Mysample,1)-1); var1=std(dim1)^2; var2=std(dim2)^2; var3=std(dim3)^2; cov(Mysample)

ans =

301.1556 78.0000 -120.2444 78.0000 268.9444 -126.9444 -120.2444 -126.9444 216.0111