how to insert an equation in a edit fill

i'm using app designerand i need that the user introduce a equation. with the variable 'x' like 2*x+1

i using this but doesn't take the equation

j=app.t.Value;

g=@(x) j;

app.c.Value=g(2);

Answer 1

[Cris LaPierre]

What do you mean by 'doesn't take the equation'? What is the expected behavior? How have you created this in app designer?

If I have to edit fields (numeric) in my app, if I set up the callback for edit field t this way, it works.

% Value changed function: t
function tValueChanged(app, event)
    j = app.t.Value;
    g=@(x) j;            
    app.c.Value=g(2);
end

The way you've written you anonymous function, it will always return the value of j no matter what value you use when calling g. So if j=5, app.c.Value is 5 despite assigning it g(2). If you want it to use the value you are passing in, update your anonymous function to use the variable you specified with '@'

g=@(x) x;

Answer 2

[Walter Roberson]

g = str2func( ['@(x)', app.t.Value]);

assuming here that app.t.Value is a character vector that is the equation in x to be evaluated.