Hi Folks, I am having some difficulties in understanding what my graph is showing me in MATLAB. I have chosen the value for a,b and c for the quadratic so the result will be complex, however the graph does not point to the values when the function cross the 0 axis. the first one does but according to the results the second should be in the third quadrant. a = 1; b = 0.009; c = 5; x =linspace(-16,16); y = a*x .* x + b*x + c plot(x,y) x1=(-b+sqrt((b^2)-(4*a*c)))/(2*a) x2=(-b-sqrt((b^2-4)*(a*c)))/(2*a) The two roots are as follows: x1 = -0.0045 + 2.2361i x2 = -0.0045 - 2.2360i x1= seems to be correct, however x2 is somewhere in the third quadrant this is not reflected on the graph generated by MATLAB. I know this is something I am doing wrong I would appreciate it, if someone will show me the error of my ways.
Did you consider the Matlab roots function? For: a = 1; b = 0.009; c = 5; Code ( (Unknown Language)): p = [1 0.009 5]; q = roots(p) q = -0.0045 + 2.2361i -0.0045 - 2.2361i Dave