Making use of the theory of continuous homotopy and the relation betwe
en symmetric polynomial and polynomial in one variable the authors dev
oted this article to constructing a regularly homotopic curve with pro
bability one. Discrete tracing along this homotopic curve leads to a c
lass of Durand-Kerner algorithm with step parameters. The convergence
of this class of algorithms is given, which solves the conjecture abou
t the global property of Durand-Kerner algorithm. The problem for step
length selection is thoroughly discussed. Finally, sufficient numerica
l examples are used to verify our theory.