Abstract: Dud (Doesn't use derivatives) algorithm was used in the paper, for determining the values of parameters in Logistic curve N=K/[1+exp(a-rt)],gener alized Logistic curve N=K/[1+exp(a-rt+bcos(pt))],expo nential piecewise curv e N=exp[α+βt+γ(t-t_c)H(t-t_c)]a nd Logistic piecew ise curve N=K/{1+exp[α+βt+γ(t-t_c)H(t-t_c)]},where t_c:change point,H(t-t_c)=0,tc,and H(t-t_c)=1,t≥t_c.Dud has advantage that it is no tnecessary to calculate the partial deriv atives of the unknown para meters.This computer program has been developed with SAS(Statistical Analysis System).

Key words: land use/cover change, landscape pattern, ecological risk, rural-urban ecotone.