I would like to write a for loop to store all values of y when A=1,2,3,4,5. into a variable y1,y2,y3,y4,y5 respectively. Any help will be greatly appreciated. Thanks

x = -3:0.1:3;
for A = 1:1:5
    y = A*sin(x);
end
plot(x,y)

Answer 1

[James Tursa]

No loop needed, and no need to create multiple variables to hold results. Just use implicit array expansion and hold results in a 2D matrix. E.g.,

x = -3:0.1:3; % row vector
A = (1:1:5)'; % column vector
y = A.*sin(x); % implicit array expansion used here, matrix = column .* row
plot(x,y)

[Rufus Adjetey]

Thanks James, But my goal is to learn how to create different variables for each vaue in a loop and not neccesarily the plot. Could you help with that. Many thanks.

[James Tursa]

Well, I could show you how to do this ... but then I would immediately recommend that you forget it and never do it. When you create dynamic variable naming like this, it makes it very hard to use downstream in the rest of your code. In short, your code will become a mess. Rather that different names, it is much better to use methods that involve indexing, such as numeric arrays (like I have shown), or cell arrays, or even structures. Please see this excellent post on the subject:

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

In the code I have shown above, instead of y1, y2, y3, etc. you would simply use y(1,:), y(2,:), y(3,:) etc.

The advantage of this indexing scheme is that it is easy to work with downstream in your code.

[Rufus Adjetey]

Thanks for your response. I know how to index and it is of no help for me doing that. I need to be able to store this in a different variable. I askded this question to understand the idea of using a for loop and creating variables. But for each variable I create, the size of variable varies based on the value in the for loop and hence I cannot use the indexing scheme although that is an easy way to do it but It will not work for the reason I need it. It clearly works with this example but not for what I intend to use it for.

Many thanks

[James Tursa]

If the variables will have different sizes, then I would suggest you first look into cell arrays. They are built using the curly braces { }. E.g., maybe something like this would work for your purpose:

A = 1:1:5;
for k=1:numel(A)
    y{k} = A(k)*sin(x);
end

Then downstream in your code you use y{1}, y{2}, etc. instead of y1, y2, etc.

So you can still use indexing in your code, and the individual cell elements y{1}, y{2}, etc. can be completely different sizes. This method is also discussed in the link I posted above.

[Rufus Adjetey]

Thank you