//exec('poly.1.ex')
//illustrate the roots format of poly
   q1=poly([1 2],'x')
   roots(q1)
//illustrate the coefficients format of poly
   q2=poly([1 2],'x','c')
   roots(q2)
//illustrate the characteristic polynomial feature
   a=[1 2;3 4]
   q3=poly(a,'x')
   roots(q3)
