Matlab r2015a guide - cannot convert double to a handle - matlab-guide

Question

In the past , I used Matlab 2013 and this code runs correctly and no errors , but now I use matlab r2015a and when I run the code, I get the following error: Cannot convert double value -10 to a handle. I checked the Matworks website but the explanation is not very clear. Do you have any suggestion on how to fix this? Thank you so much !
function minhhoaxy(action,in1)
global DATA;
if nargin < 1,
action='start';
end;
if strcmp(action,'start'),
clf reset;
figure(gcf);
set(gcf,'Units','normalized','NumberTitle','off', ...
'Name','Minh hoa GUI','backingstore','on');
min_x=-10;
max_x=10;
x=0;
uicontrol('Style','text','Units','normalized',...
'Position',[.03 .03 .1 .05],...
'BackgroundColor',[0 0.5 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'ForegroundColor','white','String','Vò trí x:',...
'HorizontalAlignment','center');
uicontrol('Style','text','Units','normalized',...
'Position',[.15 .03 .05 .05],...
'BackgroundColor',[0 0 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'HorizontalAlignment','center',...
'ForegroundColor','white','String',num2str(min_x));
x1=uicontrol('Style','slider','Units','normalized',...
'Position',[.2 .03 .25 .05],...
'SliderStep',[5.0000e-004 5.0000e-003],...
'Value',x,'Max',max_x,'Min',min_x,...
'Callback','minhhoaxy(''setx'',1);minhhoaxy(''redraw'');');
uicontrol('Style','text','Units','normalized',...
'Position',[.45 .03 .05 .05],...
'BackgroundColor',[0 0 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'HorizontalAlignment','center',...
'ForegroundColor','white','String',num2str(max_x));
x2=uicontrol('Style','edit','Units','normalized',...
'Position',[.55 .03 .09 .05],...
'FontSize',10','Fontname','VNI-Times',...
'String',num2str(x),...
'Callback','minhhoaxy(''setx'',2);minhhoaxy(''redraw'')');
uicontrol('Style','text','Units','normalized',...
'Position',[.64 .03 .05 .05],...
'BackgroundColor',[0 0 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'ForegroundColor','white','String','cm',...
'HorizontalAlignment','center');
uicontrol('Style','Pushbutton','Units','normalized',...
'Position',[.87 .03 .1 .05],...
'FontSize',12,'Fontname','VNI-Times',...
'Callback','minhhoaxy(''done'')','String','Thoaùt');
min_y=-10;
max_y=10;
y=0;
uicontrol('Style','text','Units','normalized',...
'Position',[.03 .1 .1 .05],...
'BackgroundColor',[0 0.5 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'ForegroundColor','white','String','Vò trí y:',...
'HorizontalAlignment','center');
uicontrol('Style','text','Units','normalized',...
'Position',[.15 .1 .05 .05],...
'BackgroundColor',[0 0 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'HorizontalAlignment','center',...
'ForegroundColor','white','String',num2str(min_y));
uicontrol('Style','text','Units','normalized',...
'Position',[.45 .1 .05 .05],...
'BackgroundColor',[0 0 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'HorizontalAlignment','center',...
'ForegroundColor','white','String',num2str(max_y));
uicontrol('Style','text','Units','normalized',...
'Position',[.64 .1 .05 .05],...
'BackgroundColor',[0 0 .5],...
'FontSize',12,'Fontname','VNI-Times',...
'ForegroundColor','white','String','cm',...
'HorizontalAlignment','center');
y1=uicontrol('Style','slider','Units','normalized',...
'Position',[.2 .1 .25 .05],...
'SliderStep',[5.0000e-004 5.0000e-003],...
'Value',y,'Max',max_y,'Min',min_y,...
'Callback','minhhoaxy(''sety'',1);minhhoaxy(''redraw'');');
y2=uicontrol('Style','edit','Units','normalized',...
'Position',[.55 .1 .09 .05],...
'FontSize',10','Fontname','VNI-Times',...
'String',num2str(y),...
'Callback','minhhoaxy(''sety'',2);minhhoaxy(''redraw'')');
dt=plot(x,y,'r.','EraseMode','xor','Markersize',50);
axis([-10 10 -10 10]);
grid;
DATA=[x;min_x;max_x;x1;x2;dt;y;min_y;max_y;y1;y2];
elseif strcmp(action,'redraw'),
x=DATA(1);
dt=DATA(6);
set(DATA(5),'string',num2str(x));
set(DATA(4),'value',x);
y=DATA(7);
set(DATA(11),'string',num2str(y));
set(DATA(10),'value',y);
set(dt,'XData',x);
set(dt,'YDATA',y);
drawnow;
elseif strcmp(action,'setx'),
if (in1==1),
DATA(1)=get(DATA(4),'value');
else
min_x=DATA(2);
max_x=DATA(3);
x=str2double(get(DATA(5),'string'));
if (x>max_x),
x=max_x;
end;
if (x<min_x),
x=min_x;
end;
DATA(1)=x;
end
elseif strcmp(action,'sety'),
if (in1==1),
DATA(7)=get(DATA(10),'value');
else
min_y=DATA(8);
max_y=DATA(9);
y=str2double(get(DATA(11),'string'));
if (y>max_y),
y=max_y;
end;
if (y<min_y),
y=min_y;
end;
DATA(7)=y;
end
elseif strcmp(action,'done'),
clf reset;
clear global DATA
close;
end

Answer 1

The issue is due to the fact that graphics handles used to be doubles but are now objects. Because of this, you cannot create an array that contains both numbers and graphics handles (but you used to be able to do this). If you do, MATLAB will try to convert between types and fail. Your issue is at the following line
DATA = [x; min_x; max_x; x1; x2; dt; y; min_y; max_y; y1; y2];
The dt in the middle there is a graphics handle to a plot object and is causing the error that you are seeing.
dt = plot(x,y,'r.','EraseMode','xor','Markersize',50);
To avoid this you will need to use a different data structure than a numeric array.
A much better way to handle your data and graphics handle is to use a struct or a more understandable datatype. Something like the following.
DATA.x = x;
DATA.y = y;
DATA.dt = dt;
...
Otherwise you will need to use a cell array as that can contain both objects and numbers:
DATA = {x; min_x; max_x; x1; x2; dt; y; min_y; max_y; y1; y2};

Answer 2

I had the same error message in MATLAB 2016b, i.e. Cannot convert double value 1138.95 to a handle; for use of a double array with fourier slice theorem, in image reconstruction code. It was solved by simply typing clear all in the command line.