>    restart;

>    u := (x,y) -> 1+x/(2*Pi)-sin(2*x)/12+4*(1-3/(2*Pi))*exp(-3/4*y)*sin(x/2)+2*(1/(2*Pi)-1)*exp(-3*y)*sin(x)+4/3*(1-3/(2*Pi))*sin(3/2*x)*exp(-27/4*y) +(1/(2*Pi) + 11/12)*sin(2*x)*exp(-12*y);

u := proc (x, y) options operator, arrow; 1+1/2*x/Pi-1/12*sin(2*x)+4*(1-3/2/Pi)*exp(-3/4*y)*sin(1/2*x)+2*(1/(2*Pi)-1)*exp(-3*y)*sin(x)+4/3*(1-3/2/Pi)*sin(3/2*x)*exp(-27/4*y)+(1/(2*Pi)+11/12)*sin(2*x)*e...

>    plot3d( u(x,y), x=0..2*Pi, y=0..4, labels =[`x`, `time`, `u(x,t)`], axes=framed, style=patch);

[Maple Plot]

>   

>