MATLAB: Select one root of an second degree equation

Question

i have solved a second degree equation in matlab using the roots() command and i want only one root to be displayed. How do i do this in MATLAB? Thank you very much

Answer 1

You could also use the formula for second degree equations. If the equation is:

 a*x^2 + b*x + c = 0

then get the positive root, (if there is just one,) with:

 r = (-b + sign(a)*sqrt(b^2-4*a*c))/(2*a);