error: Undefined function 'on' for input arguments of type 'double'. How can i fix this error (i use matlab app designer)?

typefunction = app.TypefunctionEditField.Editable;
a = app.aEditField.Value
b = app.bEditField.Value
run = app.RunButton.ButtonPushedFcn
error= app.errorEditField.Value
fxi=str2func(typefunction);
number_of_iterations=0;
if fxi(a)*fxi(b)>0
    result=NaN;
    return
end

if fxi(a)==0
    result=a;
    return
elseif fxi(b)==0
    result=b;
    return
end

while(abs(a-b)>=error)
    result=(a+b)/2;
    if fxi(a)*fxi(result)<0
        b=result;
    else
        a=result;
    end
    number_of_iterations=number_of_iterations+1;
end

Answer 1

[Walter Roberson]

typefunction = app.TypefunctionEditField.Editable;

fxi=str2func(typefunction);

typefunction contains something that includes "on" in function form.

Notice that you are not retrieving the text the user put into the field: you are retrieving the information about whether the field can be editted ('on') or not ('off')