2D matrix multiply with 3D array

Hi,

I have two 2D matrix u and v, and a 3D array B. I want to perform the following calculations, for example

u=rand(200,300);
v=rand(200,300);
B=rand(60,60,300)
c=0;
for j=1:300
    u1=0;
    v1=0;
    for k=1:200
        u1=u1+u(k,j)*B(:,:,k);
        v1=v1+v(k,j)*B(:,:,k);
    end
    c=c+u1.*v1;
end 

Due to two for loops, it is very slowly for the larger matrix u, v and B. Are there some good methods to compute c without using any for loop?.

Thanks a lot.

[Matt J]

Are you sure the size of B shouldn't be 60x60x200? If not, your code example ignores the final 100 pages of B.

Answer 1

[Matt J]

[m,n,p]=size(B);

Br=reshape(B,[],p);

Br=Br(:,1:200); %might not be necessary

U1=Br*u;
V1=Br*v;

c=reshape( sum(U1.*V1,2)  , m,n);

[Qiu Xu]

Thanks, I have make a mistake that the size of B should be 60x60x200. Your method is very good.