Quadratic equation in Logo

Example for versions UCBLogo 6.0

This example defines function quadraticwhich accepts coefficients of quadratic equation and prints the roots. Usage is quadratic 1 -2 1.

to quadratic :A :B :C
 if :A = 0 [(print [Not a quadratic equation.])
 stop
 ]
 make "D :B*:B - 4*:A*:C
 if :D = 0 [(print [x = ] -:B/2/:A)
 stop
 ]
 if :D > 0 [(print [x1 = ] (-:B+sqrt :D)/2/:A)
 (print [x2 = ] (-:B-sqrt :D)/2/:A)
 stop
 ]
 (print [x1 = (] -:B/2/:A [,] (sqrt (-:D))/2/A [)])
 (print [x2 = (] -:B/2/:A [,] (-sqrt (-:D))/2/A [)])
end