using a variable to call another variable

Hello all,

After doing analysis in some other software I get text files namely Eigen_1.txt, Eigen_2.txt.......Eigen_k.txt and each file is 4x4 matrix. I want to read each file, get the (1,3) value and assign it to variable T1_1, T1_2.......T1,k and then use this value to get omega1_1 and so on. I have used eval command which works fine, but is there any other way to solve this without using eval command.

for n = 1:k

temp = readmatrix(strcat('.\Results\Eigen_',num2str(n),'.txt'),'delimiter',' ');

eval(['T1_',num2str(n),'=temp(1,3)']);

eval(['omega1_',num2str(n),' = 6.2832/T1_',num2str(n),]);

end

[Stephen23]

"I have used eval command which works ..."

not very well: dynamically accessing variable names like that requires writing code which is slow, inefficient, insecure, obfuscated, buggy and hard to debug:

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

"...but is there any other way to solve this without using eval command."

The name MATLAB comes from MATrix LABoratory, so the simple and obvious solution is to use matrices, just like MATLAB is designed for. This is exactly what the introductory tutorials show too:

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

[Irshad Qureshi]

I agree with you and will go through tutorials. I am a novice in MATLAB so still learning.

Thanks,

[Stephen23]

@Irshad Qureshi: you might find this useful:

https://www.mathworks.com/matlabcentral/answers/228557-experts-of-matlab-how-did-you-learn-any-advice-for-beginner-intermediate-users

[Irshad Qureshi]

thanks, Stephen.

Answer 1

[Chunru]

T1 = zeros(k, 1);           % use array instead of T1_, T1_2, ...
omega1 = zeros(k, 1);   
for n = 1:k
    temp = readmatrix(strcat('.\Results\Eigen_',num2str(n),'.txt'),'delimiter','  ');
    %     eval(['T1_',num2str(n),'=temp(1,3)']);
    %     eval(['omega1_',num2str(n),' = 6.2832/T1_',num2str(n),]);
    T1(n) = temp(1, 3);
    omega1(n) = 2*pi/T1(n);
end

[Irshad Qureshi]

Thanks. Its working and its much easier also.