xx=var('xx')
N=5
bbn=[32/(((2*n-1)^3)*pi^3) for n in range(1,N+1)]
u=sum(bbn[n]*exp(-1.14*((2*(n+1)-1)/2*pi)^2*t)*sin((2*(n+1)-1)/2*pi*xx) for n in range(0,N))
P2=plot(u.substitute(t==0),[xx,0,1],color='green');
P3=plot(u.substitute(t==0.01),[xx,0,1]);
P4=plot(u.substitute(t==0.08),[xx,0,1]);
P5=plot(u.substitute(t==0.2),[xx,0,1]);
P6=plot(u.substitute(t==0.6),[xx,0,1]);
P7=plot(u.substitute(t==1.0),[xx,0,1]);
P8=plot(u.substitute(t==1.5),[xx,0,1]);
P9=plot(u.substitute(t==2.0),[xx,0,1]);
(P2+P3+P4+P5+P6+P7+P8+P9).show()
plot3d(u,[xx,0,1],[t,0,2],plot_points=[20,20],aspect_ratio=(1,1,0.2),mesh=True)