create different vector using for loop

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MUKESH KUMAR
MUKESH KUMAR 2017-8-1
回答： Jan 2017-8-1
I have three users named A1, A2 and A3 and each user has three appliances like A11 represent the A1's 1st appliance and A12, A13 similarly A21, A22, A23, and A31, A32, A33. I have the following matrix A11=[1 1 1 1 2]; A12=[1 2 2 2 2]; ......so on. so how can i use for loop for excessing these vectors and if these data in excel then how can we excess?
  2 个评论
Stephen23
Stephen23 2017-8-1
Do NOT waste your time writing bad code that creates separate variables with numbered variable names: "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."
source: http://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html
Just use indexing: simple, fast, efficient, neat, simple, easy to understand, much less buggy, easier to debug, etc, etc, etc.
https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
https://www.mathworks.com/matlabcentral/answers/143-how-do-i-make-a-series-of-variables-a1-a2-a3-a10
https://www.mathworks.com/matlabcentral/answers/57445-faq-how-can-i-create-variables-a1-a2-a10-in-a-loop
etc, etc, etc.

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回答（1 个）

Jan
Jan 2017-8-1
Don't do this. The question is asked several times each week, and the answer is always the same. Do not hide an index in the name of a variable. Use an index instead.
Please read the linkls posted by Stephen and see also https://www.mathworks.com/help/matlab/matlab_prog/techniques-for-improving-performance.html:
Avoid functions such as eval, evalc, evalin, and feval(fname). Use the function
handle input to feval whenever possible. Indirectly evaluating a MATLAB expression
from text is computationally expensive.

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