@vv

 it works perfectely, thanks for your help. Now i could plot w in term of z . I am really grateful. 

@Mikael Hakman 

your right , but the problem is that i could not find an explicit function like g^(-1)(z)=r. because g(r) is a complicateted function . on the other word, maple could not solve ( z-g(r)=0, r) just could solve it numerically,

@YasH 

of course not, I want to plot w in term of z not f vesus g. so I think it not obey the link you mentioned.