Cell Array and Matrix Multiplication

Here is my question/problem:

I need to multiply several 4x4 matrices together in order based on some data. I have a loop that constructs a 1 x n cell array with each cell being a 4x4 matrix.

for i = 1:n

    ct = cos(dh.t(i+1));
    st = sin(dh.t(i+1));
    cf = cos(dh.f(i));
    sf = sin(dh.f(i));
    a = dh.a(i);
    d = dh.d(i+1);
    A = [ct   ,   -st,   0,     a;
         cf*st, cf*ct, -sf, -sf*d;
         sf*st, sf*ct,  cf,  cf*d;
         0    ,     0,   0,     1];
    B(1,i) = {A};
end

A is the matrix for each iteration i and is stored in the cell array B. I need each of the matrices in B to be multiplied by each other in order and return a single 4x4 matrix ( i.e. T = B{1,1}*B{1,2}*B{1,3}*...*B{1,n} ). I am not sure how to do this for a general case n. I am not even sure if what I did above is the best way to do this problem, but that's what I have done so far.

Thanks for any help.

Answer 1

[the cyclist]

If everything is numeric, do you really need to use cell arrays (which then need to be "unpacked" to do the numeric calculation again)? Or could you do something like:

 B = zeros(4,4,n);
 T = eye(4);
 for i = 1:n
     blah blah
     B(:,:,i) = A;
     T = T*B(:,:,i);
 end

It is not clear what, if any, of the intermediate results you need to ultimately store, so you may not even to keep B at all.

[Brian]

Awesome. This is much better than what I was trying to do. Thanks for the help.