MATLAB: Automatically define (global) variables

defineglobal variablesMATLAB

I would like to define several global variables (P1,P2,P3,…,Pn), where n is a number to be defined. I my first attempt was the following one:

 for i = 1:n
      global strcat('P',num2str(i))
 end

This does not work, what is the proper way to do this?

Best Answer

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

https://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html

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MATLAB: How to write a1=1;a2=2;a3=3; from A

Do NOT do this

This would actually be horribly slow, pointlessly complex, obfuscated, and very buggy way to write your code. You would make your code hard to debug, and a pain to work with. Read this to know why:

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

Using indexing would be simple, neat, and very efficient. You should use one array and indexing. Indexing is the solution you should be using, because it is the most efficient way to write MATLAB code, is simple, neat, and very easy to debug. Indexing is explained quite well in the MATLAB introductory tutorials, which are highly recommended for all beginners:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

MATLAB: I have variables ‘Ereal2’,Ereal3,Ereal4,Ereal5.….so on…..how to call these variable in a single loop one by one.

Hi Ravi

I have to agree with Jonas. But if you insist to use indexing which is embedded to the variable name, you can take some ideas from the following piece of code

clear; clc;
for n=1:10
      % assign a value to each variable 
      strcmd=['Ereal' num2str(n) '=n^2 ;'];
      eval(strcmd);
      % display the value of each variable 
      disp(['Ereal' num2str(n) ' = ' num2str(eval(['Ereal' num2str(n)]))]);
end

The "key idea" is eval() function. You can find more info about this function on Mathworks help files

Best Answer

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MATLAB: How to write a1=1;a2=2;a3=3; from A

MATLAB: I have variables ‘Ereal2’,E​real3,Erea​l4,Ereal5.​….so on…..how to call these variable in a single loop one by one.

Related Question

MATLAB: I have variables ‘Ereal2’,Ereal3,Ereal4,Ereal5.….so on…..how to call these variable in a single loop one by one.