How can i input value in symbolic expression, automatically?

Hi. I'm not good at MATLAB. so it's hard to me...

I make symbolic expression, bou I have some trouble.

syms a [1 2]
syms 'a_x%d' [2 3]

When I code like above, I can get like below.

And I input values to symbolic expression, it is not work that I wanted.

for i = 1:2
    for j = 1:3
        a_x(i,j) = i+j
    end
    a(i) = i
end

Then, the result is below.

a_x =
 
[2, 3, 4]
[3, 4, 5]
 
 
a =
 
[1, 2]

But I want likt this like below, automatically.

a_x11 = a_x(1,1)

a_x12 = a_x(1,2)

a_x13 = a_x(1,3)....

a1 = a(1)

a2 = a(2)

How can I do it??

Answer 1

[Walter Roberson]

We recommend against that.

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

In the specific case of symbolic work, code

for i = 1:2
    for j = 1:3
        a_x_val(i,j) = i+j;
    end
    a_val(i) = i;
end

and continue to compute with a_x and a symbolic in your code. When you get to the point where the code needs a specific value for the variables,

subs(expression, [a; a_x(:)], [a_val; a_x_val(:)])

Putting all the variables together like [a; a_x(:)] is needed in order to get proper simultaneous substitution.

[연승 김]

Thank you for your kind and quick reply!!

I know and studied about the 'subs' function, but I cannot think of applying..

It means I'm novice...beginner.

Thank you again for your answer!! Have a nice day!