Filling up a vector

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alpedhuez
alpedhuez on 27 Mar 2018
Commented: Stephen23 on 2 Apr 2018
Suppose I have 1 by 2N vector
x=zeros(1,2*N);
Now I have N of 1 by 2 vector
y1=ones(1,2), y2=ones(1,2)
and I want to fill x as
[y1 y2 ...]
what will be a compact way to fill x in this way (instead of concatenation)?
  1 Comment
Stephen23
Stephen23 on 2 Apr 2018
Do NOT do this! The MATLAB documentation specifically advises against what you are trying to do: "A frequent use of the eval function is to create sets of variables such as A1, A2, ..., An, but this approach does not use the array processing power of MATLAB and is not recommended. The preferred method is to store related data in a single array"
Read this to know more:

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Answers (1)

Walter Roberson
Walter Roberson on 27 Mar 2018
x(1:2:end) = y1;
x(2:2:end) = y2;
or
x = reshape([y1; y2], 1, []); %requires that y1 and y2 be row vectors
or
x = reshape([y1(:), y2(:)].', 1, []); %does not requires that they be row vectors
  3 Comments
Walter Roberson
Walter Roberson on 28 Mar 2018
Edited: Walter Roberson on 28 Mar 2018

http://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Though I see now that I misinterpreted your question -- I thought you wanted alternating elements, but instead you were looking for dynamic variable names.

alpedhuez
alpedhuez on 28 Mar 2018
Let me think about it and phrase questions in a clearer way. Thank you.

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