Problem to create a matrix

Question

Avelino 2011-10-28

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https://ww2.mathworks.cn/matlabcentral/answers/19665-problem-to-create-a-matrix

Hello,

I am trying to create a matrix in Matlab e.g., A with 300 lines and 780 columns. I have also one other one, that is just one column B with 780 lines. I wanted to create a matrix A that goes in 0.02, i.e., 0; 0.02 (...) to B(1). This in the first line. In the second one something like A(780) + 0.02 and further till i=300. My approach in matlab was the following:

for i=1:300 for j=780 A(i,j) = B(i):0.02:B(i+1) end end

With this, MatLab is presenting me an error of the dimensions: ??? Subscripted assignment dimension mismatch.

If somebody could help me, I really would appreciate :)

Thank you!

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Daniel Shub 2011-10-28

It is unclear what you want your matrix to look like. Can you edit the question to include a few more "lines" (these are often called "rows") of the desired matrix. From your example it is unclear why matrix A would have 780 columns. It is possible that 0, 0.02, ..., B(1) would have 780 elements, but in general it will not. Further, A(780)+0.02 will definitely not have 780 elements.

Avelino 2011-10-28

Hello Daniel,

Thank you. Now I just realize that I make mistake, the Matrix B have 300 lines.

It should look something like this, let's say that:

B =

16

32

48

in this case A should look like

A =

0 0.02 (...) 16 (with 800 columns)

16 16.02 (...) 32 (with 800 columns)

32 32.02 (...) 48 (with 800 columns)

This example is slightly different from mine as I have 780, but the method is the same.

Thank you very much,

Avelino

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Answer 1

Andrei Bobrov 2011-10-28

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在 MATLAB Online 中打开

B = (1:300)'*16;
A = bsxfun(@plus,B-16,0:.02:B(1));

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Daniel Shub 2011-10-28

I always forget about bsxfun. I have only recently started to remember about arrayfun.

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Answer 2

Daniel Shub 2011-10-28

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https://ww2.mathworks.cn/matlabcentral/answers/19665-problem-to-create-a-matrix#answer_26027

在 MATLAB Online 中打开

Does this do what you want?

B = (1:300)*16;
A = cell2mat(arrayfun(@(x)plus(x, 0:0.02:(16-0.02)), B, 'UniformOutput', false)')-16;

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