When we plot z = f(x), where x and z are complex numbers, we get 4 dimensions to plot, so I shifted each point in the surface plot N units + or - in the Y direction, where N is the imaginary part of the output. The color also indicates how far each point was stretched in the + or - Y direction.
#!/usr/bin/octave global a = 1 global b = 0 global c = 0 function z = polynomial (i,j) global a global b global c x = i + (j * 1j); z = a*x*x + b*x + c; end [I,J] = meshgrid(-1:0.2:1); REAL = arrayfun(@real, arrayfun(@polynomial, I, J)); IMAG = arrayfun(@imag, arrayfun(@polynomial, I, J)); vtk_surf(I,J+IMAG,REAL, IMAG); input ("Orient it the way you want it before I save."); vtk_print('polynomial.jpg', '-djpeg'); input ("Done!");