stacking of large matrix into stack of small column matrix

Hello here i want to put row of w matrix as a column vector in w_stack for i as a number of element. i.e each row of w corresponds to each element which i want it a column vector. can you please help me

nele = 8;

w = zeros(nele,3);

w = [0 0 0;

0 0 0;

0 0 0;

0 0 0;

0 0 -2;

0 0 -2;

0 0 -2;

0 0 -2];

w_trans = w';

W = w_trans(:);

w_stack = zeros(3,1,nele);

for i = nele

w_stack(1:3,1,i) = w(1:w(1:3, 1, i)';

end

Answer 1

[DGM]

I'm not really sure what exactly you want, but I'm going to take a guess anyway. I'm going to assume that nele is possibly less than size(w,1). I'm going to interpret your original prototype code as to be:

nele = 8;
w = [0 0 0;
    0 0 0;
    0 0 0;
    0 0 0;
    0 0 -2;
    0 0 -2;
    0 0 -2;
    0 0 -2];

w_stack = zeros(3,1,nele);
for i = 1:nele
    w_stack(:,1,i) = w(i,:);
end
w_stack

w_stack = 
w_stack(:,:,1) =

     0
     0
     0


w_stack(:,:,2) =

     0
     0
     0


w_stack(:,:,3) =

     0
     0
     0


w_stack(:,:,4) =

     0
     0
     0


w_stack(:,:,5) =

     0
     0
    -2


w_stack(:,:,6) =

     0
     0
    -2


w_stack(:,:,7) =

     0
     0
    -2


w_stack(:,:,8) =

     0
     0
    -2

If that's a correct interpretation of your goal, then you can replace that with one line:

wstack = permute(w(1:nele,:),[2 3 1])

wstack = 
wstack(:,:,1) =

     0
     0
     0


wstack(:,:,2) =

     0
     0
     0


wstack(:,:,3) =

     0
     0
     0


wstack(:,:,4) =

     0
     0
     0


wstack(:,:,5) =

     0
     0
    -2


wstack(:,:,6) =

     0
     0
    -2


wstack(:,:,7) =

     0
     0
    -2


wstack(:,:,8) =

     0
     0
    -2

... and the results are the same.