如何化三维概率密度函数的图

函数如下：f(y,u)=[20*y*exp(-10*(1 u.^2)*y) 0.399*exp(-(y-1.5)^2/(0.1*(1 u)^2))]/g(u);g(u)=0.05*(1 u) 40*[(1-1/(5 5*u^2))*exp(-10*(1 u^2)) 1/(5 5*u.^2)]/(5 5*u.^2);u在[0，1]；y在[0，2],如何在matlab下画出f(y,u)的三维图形呢？答案如下：function ff=fig2% 绘制如下概率密度分段函数：% p(x,y)=[p1(x,y),p2(x,y),p3(x,y)]% p1(x,y)=[0.5457*exp(-0.75*y^2-3.75*x^2-1.5x),(x y>1)];% p2(x,y)=[0.7575*exp(-y^2-6*x^2),(-1<x y<=1)]; % p3(x,y)=[0.5457*exp(-0.75*y^2-3.75*x^2 1.5x),(x y<=-1)];[x,y]=meshgrid(-1.5:.1:1.5,-2:.1:2);z= 0.5457*exp(-0.75*y.^2-3.75*x.^2-1.5*x).*(x y>1) ...0.7575*exp(-y.^2-6*x.^2).*((x y>-1)