having problems troubleshooting this code (vertcat syntax)

I've been having trouble making this code work, I am trying to make a program that returns the roots of a polynominal, along with if the roots are complex or not based on the discriminant. I keep getting the 'vertcat' syntax. can anyone help point out the error in my code?

function [r] = quadratic(~)
    q_fields = {'Coefficient "a"',...
        'Coefficient "b"',...
        'Coefficient "c"'};
    tboxtitle = 'Coefficient Input Menu';
    
    co_values = inputdlg(q_fields,tboxtitle);
    
    a = str2num(co_values{1});
    b = str2num(co_values{2});
    c = str2num(co_values{3});
    
    x1 = (-1*b + (sqrt(b^2.-(4*a*c))))/(2*a);
    x2 = (-1*b - (sqrt(b^2.-(4*a*c))))/(2*a);
    
    x1 = num2str(x1);
    x2 = num2str(x2);
    
    d = b^2.- (4*a*c);
    d = num2str(d);
    
    if d > 0
        r = msgbox(['The roots for your selected coefficients are ',x1,' and ',x2; ...
            'There are 2 real roots']); 
    elseif d == 0
        r = msgbox(['The roots for your selected coefficients are ',x1,' and ',x2; ...
            'There is 1 real root']); 
    elseif d < 0
        r = msgbox(['The roots for your selected coefficients are ',x1,' and ',x2; ...
            'There are 2 imaginary roots']); 
        
    end
end

Answer 1

[Stephan]

function [r] = quadratic(~)
    q_fields = {'Coefficient "a"',...
        'Coefficient "b"',...
        'Coefficient "c"'};
    tboxtitle = 'Coefficient Input Menu';
    
    co_values = inputdlg(q_fields,tboxtitle);
    
    a = str2num(co_values{1});
    b = str2num(co_values{2});
    c = str2num(co_values{3});
    
    x1 = (-1*b + (sqrt(b^2.-(4*a*c))))/(2*a);
    x2 = (-1*b - (sqrt(b^2.-(4*a*c))))/(2*a);
    
    x1 = num2str(x1);
    x2 = num2str(x2);
    
    d = b^2.- (4*a*c);
    d = num2str(d);
    
    if d > 0
        r = msgbox(['The roots for your selected coefficients are ',x1,' and ',x2, ...
            'There are 2 real roots']);                                      %   ^
    elseif d == 0                                                            %   |
        r = msgbox(['The roots for your selected coefficients are ',x1,' and ',x2, ...
            'There is 1 real root']);                                        %   ^   
    elseif d < 0                                                             %   |
        r = msgbox(['The roots for your selected coefficients are ',x1,' and ',x2, ...
            'There are 2 imaginary roots']);                                 %   ^   
                                                                             %   |
    end                                                                      %   |
end                                                                          % HERE , instead ;

[Steven Lord]

That will put all the text on one line. If the intent was to put the second part on a separate line, I'd replace the semicolon with newline. As an example of what this looks like for one of those lines:

r = msgbox(['The roots for your selected coefficients are ',x1,' and ',x2, newline, ...
    'There are 2 real roots']); 

[Bailey Owen Banks]

Thank you Stephen!

I found a workaround shortly after posting - put { } brackets after the msgbox command , as shown. Rinse and repeat for the other conditional statements - but thank you nonetheless!!

r = msgbox({['The roots for your selected coefficients are ' ...
            ,x1,' and ',x2];'There are 2 real roots'});

[Stephan]

Why not post your solution as an answer. May be interesting for others facing the same problem.