Conversion to matlab.ui.control.EditField from matlab.ui.Root is not possible.

Question

Nittya Ananda 2023-2-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1918130-conversion-to-matlab-ui-control-editfield-from-matlab-ui-root-is-not-possible

回答： Simon Chan 2023-2-24

I am trying to write an app for lagrange's multiplier. It shows error in the last line.

please help!

function ButtonPushed(app, event)
            syms x y lambda;
            f=app.fEditField.Value;
            func=str2sym(f(1));
            g=app.gEditField.Value;
            cons=str2sym(g(1))==0;
            L = func + lambda*lhs(cons);
            %L=str2sym(l);
            dL_dx=diff(L,x)==0;
            dL_dy=diff(L,y)==0;
            dL_dlambda=diff(L,lambda)==0;
            system = [dL_dx; dL_dy; dL_dlambda];
            [x_val, y_val,lambda_val] = solve(system, [x y lambda], 'Real', true);
            results_numeric = double([x_val, y_val, lambda_val]); % show results in a vector of data type double
[row,col]=size(results_numeric);
max=0;
min=0;
a=0;
x_min=results_numeric(1,1);
x_max=results_numeric(1,1);
y_min=results_numeric(1,2);
y_max=results_numeric(1,2);
max=subs(subs(func,x,results_numeric(1,1)),y,results_numeric(1,2));
min=max;
for i=2:row
    a=subs(subs(f,x,results_numeric(i,1)),y,results_numeric(i,2));
    if(a>max)
        max=a;
        x_max=results_numeric(i,1);
        y_max=results_numeric(i,2);
    elseif(a<min)
        min=a;
        x_min=results_numeric(i,1);
        y_min=results_numeric(i,2);
    end
end
% x1=-10:0.1:10;
% y1=x1';
% [X1,Y1]=meshgrid(x1,y1);
% z1 = subs(f, {x, y}, {X1, Y1});
% z2= subs(g, {x, y}, {X1, Y1});
% surf(app.UIAxes,X1,Y1,double(z1));
d=double(max);
app.outputEditField=d; [this is where I get the error.]
error:
The following error occurred converting from matlab.ui.Root to matlab.ui.control.EditField:
Conversion to matlab.ui.control.EditField from matlab.ui.Root is not possible.