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How do I create and store data into a new row after every loop?

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Jaydeep Dutta
Jaydeep Dutta 2017-12-23
评论： Jaydeep Dutta 2017-12-23
For example:
I am trying to update the old variable matrix but I am getting an error
f = [1 2 3 4];
a = [1 2 3 4 5 6];
old = 0;
for i = 1:length(a)
new = f.*a(i);
old(:,i) = new;
end
I want an old matrix with these values
{1 2 3 4;2 4 6 8;3 6 9 12;4 8 12 16;5 10 15 20; 6 12 18 24}
thank you

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Walter Roberson
Walter Roberson 2017-12-23
To deliberately grow the old matrix, either initialize
old = zeros(length(f),0);
or else do not initialize old at all. With what you are doing now, you are initializing old as having only one row, but then trying to write multiple rows to it.
More efficient would be to initialize the entire matrix
old = zeros(length(f), length(a));
This would not grow the matrix as you went: it would start it out as the proper size.
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Walter Roberson
Walter Roberson 2017-12-23
To get that error, you must be using a very old MATLAB, such as from 2009.
Try
old(:,i) = new .';
Jaydeep Dutta
Jaydeep Dutta 2017-12-23
I should have mentioned earlier..I'm currently using a Matlab v6.1 My apologies and thats a lesson learned Thank you very much :)

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