; Simple example show how sensitive polynomial roots
; are to the coefficients.
; Try
;   c = 0        roots x = 0, 3, 4, 5
;   c = 24       roots x = 1, 0.8883
;   c = 24.1     no roots

 x^4 - 12x^3 + 47x^2 - 60x + c = 0
 c = 24.
 -100 < x < 100
 PROGRESS x