Displaying complex roots of quadratic equation

This is my code.

a = input ('enter a: ');
b = input ('enter b: ');
c = input ('enter c: ');
xmin = input ('enter xmin: ');
xmax = input ('enter xmax: '); 

step = (xmax - xmin)/100;
x = xmin : step : xmax;
y = a.*x.^2 + b.*x + c;

plot (x,y);
grid on;
xlabel ('x') ;
ylabel ('y');
xtickangle (45);

title (['Plot of f(x) = ', num2str(a), 'x.^2 + ', num2str(b), 'x + ', num2str(c)]);

D = b^2 - 4*a*c;

if D >= 0
    x1 = (-b + sqrt (D)) / (2*a);
    x2 = (-b - sqrt (D)) / (2*a);
    fprintf ('Real zeros: %g, %g, \n', x1, x2)
    fprintf ('Factored Form: f(x) = (x - %g)(x - %g) \n', x1, x2)

else
    x1 = (-b + sqrt (D)) / (2*a);
    x2 = (-b - sqrt (D)) / (2*a);
    fprintf ('Complex Zeroes: %g, %g, \n', x1, x2)
    fprintf ('Factored Form: f(x) = (x - (%g))(x - (%g)) \n', x1, x2)
end

When I have a quadratic with complex roots, the last line of the code only displays the real part of the root. Why? How can I change it so it displays both the real and imaginary part?

Answer 1

[Roger Stafford]

On that 'else' part you need to find the two values real(x1) and imag(x1) as well as these two for x2. Then provide a display of all four quantities in each of your 'fprintf' lines. You might have something like this:

fprintf('Complex Zeros: %g + i*%g, %g + i*%g\n',real(x1),imag(x1),real(x2),imag(x2))