merging column vectors from the loop in to a single matrix

Every iteration my algorithm gives me a column vector and I want to form a new matrix composed of these column vectors together sequentially ( for example, the third column vector from the iteration will be the third column in the newly formed matrix). I will be thankful if anyone suggest me how to write a loop which can do so.

Abex

Answer 1

[Matt Tearle]

% preallocate space
x = zeros(m,n);

% iterate <=> loop over columns
for k = 1:n
   y = ... % make vector here
   x(:,k) = y;  % store y as kth column of x
end

This is assuming you know how many iterations you will have. If not, you may suffer some performance degradation, but:

x = [];
while ...
   y = ...
   x = [x,y];
end

Answer 2

[Michael]

Try something like:

matrix = zeros(rows, columns); % preallocate your matrix
for i = 1:columns
    column = [your code here generates a 1 x rows matrix];
    matrix(:,i) = column;
end

I think I got everything the right way around. The second line inside the loop saves the current column as the i^th column in the matrix. The first line should help for speed if you have many columns.