% p21: square root branch cut; 04/02/2008 SGLS
x = -2:.01:2; y = x;
[x,y] = meshgrid(x,y); z = x + i*y;
f = sqrt(z);
surf(x,y,imag(f)); shading flat
xlabel('Re z'); ylabel('Im z'); zlabel('Im \sqrt {z}')
