如何使用3D圖

Question

繪製在楓的函數（偏導數），我有以下功能

u := proc (x, t) options operator, arrow; 
    50+sum((100*n*Pi*sin(n*Pi)+100*cos(n*Pi)-100)*cos((1/10)*n*Pi*x)*exp(-(1/100)*n^2*Pi^2*t)/(n^2*Pi^2), n = 1 .. 20) 
    end proc; 

plot3d(u(x, t), x = 0 .. 10, t = 0 .. 20) 

我試圖繪製它的楓葉，但不給我正確的3D形狀。

Answer 1

restart: 
u := proc (x, t) options operator, arrow; 
    50+sum((100*n*Pi*sin(n*Pi)+100*cos(n*Pi)-100)*cos((1/10)*n*Pi*x)*exp(-(1/100)*n^2*Pi^2*t)/(n^2*Pi^2), n = 1 .. 20) 
    end proc: 

plot3d(u(x, t), x = 0 .. 10, t = 0 .. 20); 

plot3d(diff(u(x, t),x), x = 0 .. 10, t = 0 .. 20);