MATLAB: Hey can you please help me with these errors im getting from the GUI

Question

function varargout = diffyQ(varargin)
% DIFFYQ MATLAB code for diffyQ.fig
%      DIFFYQ, by itself, creates a new DIFFYQ or raises the existing
%      singleton*.
%




%      H = DIFFYQ returns the handle to a new DIFFYQ or the handle to
%      the existing singleton*.
%
%      DIFFYQ('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in DIFFYQ.M with the given input arguments.
%
%      DIFFYQ('Property','Value',...) creates a new DIFFYQ or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before diffyQ_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to diffyQ_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES
% Edit the above text to modify the response to help diffyQ
% Last Modified by GUIDE v2.5 12-Apr-2018 12:08:25
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @diffyQ_OpeningFcn, ...
                   'gui_OutputFcn',  @diffyQ_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end
if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT
% --- Executes just before diffyQ is made visible.
function diffyQ_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure

% eventdata  reserved - to be defined in a future version of MATLAB




% handles    structure with handles and user data (see GUIDATA)



% varargin   command line arguments to diffyQ (see VARARGIN)
% Choose default command line output for diffyQ
handles.output = hObject;
% Update handles structure
guidata(hObject, handles);
% UIWAIT makes diffyQ wait for user response (see UIRESUME)
% uiwait(handles.figure1);
% --- Outputs from this function are returned to the command line.
function varargout = diffyQ_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Get default command line output from handles structure
varargout{1} = handles.output;
function input_Callback(hObject, eventdata, handles)
% hObject    handle to input (see GCBO)

% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of input as text
%        str2double(get(hObject,'String')) returns contents of input as a double
% --- Executes during object creation, after setting all properties.
function input_CreateFcn(hObject, eventdata, handles)
% hObject    handle to input (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end
% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
x= str2double(get(handles.input,'string'));
diffyEQ = solve(x);
num2str(set(handles.solution, 'string', diffyEQ));
      function diffyEQ = solve(x)
  syms t;
  x2=diff(x);
   diffyEQ = dsolve('(D2y)+(3*Dy)+(2*y)= x2', 'Dy(0) = -5 ','y(0) = 0');
   pretty(diffyEQ)

These are my errors

Error while evaluating UIControl Callback.
x2                                / x2     \
-- - exp(-t) (x2 + 5) + exp(-2 t) | -- + 5 |
 2                                \  2     /
Error using matlab.ui.control.UIControl/set
Error setting property 'String' of class 'UIControl':
Value must be a character array, numeric array, or cell array.
Error in diffyQ>pushbutton1_Callback (line 105)
num2str(set(handles.solution, 'string', diffyEQ));
Error in gui_mainfcn (line 95)
        feval(varargin{:});
Error in diffyQ (line 42)
    gui_mainfcn(gui_State, varargin{:});
Error in
matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)diffyQ('pushbutton1_Callback',hObject,eventdata,guidata(hObject)) 
Error while evaluating UIControl Callback.

Answer 1

Change

num2str(set(handles.solution, 'string', diffyEQ));

to

set(handles.solution, 'String', char(diffyEQ));