On MATLab app designer, how can i get an editfield text as a variable?

Hello, I have am developing a matlab app, where the app user inputs a function to an edit field, and i need to use whatever that function is in a later part of the code. The problem is that the editfield outputs as text rather than a variable/function. Does anyone know how can I output it as a variable?

The code is as follows:

So say user inputs to EditField: x(1)^3 + x(2)^2

Then I want to set: val = app.EditField.Value;

However, this gives me the text: val = 'x(1)^3 + x(2)^2'

When i want: val = x(1)^3 + x(2)^2

Is this possible? Thanks for the help.

[Fangjun Jiang]

Do you mean you have x defined,e.g. x=1:3, you want to Val=1^3+2^2=5?

or do you want val=f(x)=x(1)^3 + x(2)^2 as a function handle?

[Eoghan Summers]

Yes, x is defined. The "val = x(1)^3 + x(2)^2" is passed to another function, for which values of x are input.

Answer 1

[Fangjun Jiang]

EditFieldText='x(1)^3 + x(2)^2';
F=str2func(['@(x)',EditFieldText]);

Then pass the function handle F to another function and use it. You don't have to worry about variable name x.

>> y=1:3
y =
     1     2     3
>> F(y)
ans =
     5

or you can pass EditFieldText over to the other function and construct the function handle there

Answer 2

[Arthur Roué]

If you want to evaluate an expression in a string, check for eval or evalin functions.

For instance :

x = [1 2];
str = 'x(1)^3 + x(2)^2';
val = eval(str);

[Eoghan Summers]

Yes! That works perfectly, thank you very much

[Dennis]

It might be worth to mention that this might cause problems down the road depending on your apps users. eval will evaluate any expression entered - including for example system commands.