How can I differentiate in app designer?

Hello, I am unable to differentiate a function of x in the app designer specifically. I can do so in the base command window, yet I run into issues trying to do so in the app designer. The app returns with several seemingly random values. I have my code posted below. Any help is greatly appreciated. For context, I am trying to create an app that will differentiate any function of x, and later I plan to have it evaluate both graphs at a given point of x.

function ExecuteButtonValueChanged(app, event)

syms x

f = app.FxEditField.Value;

g=diff(f);

fplot(app.graph, f);

fplot(app.first_deriv,g);

end

Answer 1

[Eric Delgado]

You missed the string to symbolic expression convertion...

% Instead of:
f = app.FxEditField.Value;

% Try:
f = str2sym(app.FxEditField.Value);