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From: Walter Roberson on 14 May 2010 17:53
Joseph wrote:

> Consider storing data in a cell array with a double-for loop, thusly:
>
> count = 0
> for j = 1: n
> for i = 1:m
> count = count+1;
> B{count,1} = {d{j}, ei}, F(i,j) };
> end
> end

Did you preallocate? Even just

B = cell(n*m,1);

would be faster than not preallocating.

> In any event, I vectorized the problem successfully, but it really
> didn't speed things up.

Could we see the vectorized version? We might (or might not) see a faster way
to do it.
From: Jan Simon on 15 May 2010 10:18
Dear Joseph!

> count = 0
> for j = 1: n
> for i = 1:m
> count = count+1;
> B{count,1} = {d{j}, ei}, F(i,j) };
> end
> end

This line is not valid:
B{count,1} = {d{j}, ei}, F(i,j) };
I assume you want this:
B{count,1} = {d{j}, e{i}, F(i,j) };
Are you sure, that you want to create a cell, which contains cells:
B = {{d{1}, e{1}, F(1, 1)}; {d{1}, e{2}, F(2, 1)}; ...}
?? Perhaps you could reperesent your data faster as:
B = {d{1}, e{1}, F(1, 1);
d{1}, e{2}, F(2, 1); ...}

d{j} does not change in the inner loop, so it is faster to move it outside:
B = cell(n * m, 1);
count = 0
for j = 1:n
dj = d{j};
for i = 1:m
count = count+1;
B{count} = {dj, e{i}, F(i,j)}; % No need for B{count, 1}
end
end

I'm interested how you have vectorized this.

Kind regards, Jan
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