从无粘性的 Burgers 方程：$\frac{\partial u}{\partial t}+u\frac{\partial u}{\partial x} = 0$，我得到了离散化$\frac{u_i^{n+1}-u_i^n}{\Delta t}+\frac{(u_i^{n+1})^2-(u_{i-1}^n)^2}{\Delta x}=0$. 有起始条件$u_0(x)=sin(\pi x)$,$x\in[0,1]$, 我想绘制$u$后$n$时间步长。但是，我似乎无法让它工作，并希望得到任何帮助。Python代码：

import numpy as np
import matplotlib.pyplot as plt
import scipy as py
from scipy.sparse.linalg import gmres

#x
x0 = 0 #x min
xe = 1 #x max
N = 100 #Nodes
dx = (xe-x0)/N 
x = py.linspace(x0,xe,N)

#t
t0 = 0 #time
te = 1 #max time
dt = 0.0001 #timestep
M = int((te-t0)/dt) #timesteps

#u
u0 = py.sin(py.pi*x)

ts = 50

def EulerMethod(ustart):
    U = np.zeros((N,M))
    U[:,0] = ustart
    t=t0
    for i in range(N-1): #one step Euler forward
        U[0,1] = 0
        U[i+1,1] = U[i+1,0] - (dt/dx)*(U[i+1,0]**2-U[i,0]**2)
    for n in range(ts):
         U[:,n+2] = NewtonMethod(U[:,n+1],U[:,n]) #Eulers implicit method with Newtons Method        
         t=t+dt
    return U

def NewtonMethod(u,c):
    #c = u_n
    for i in range(3):
        F = np.zeros((N,1))
        J = np.zeros((N,N))
        J[N-1,N-1] = 1/dt + u[N-1]/dx
        F[0] = (u[0] - c[0])/dt + (u[0]**2)/2*dx
        for j in range(N-1):
            J[j,j] = 1/dt + u[j]/dx
            J[j+1,j] = 1/dt + u[j]/dx
            F[j+1] = (u[j+1] - c[j+1])/dt + (u[j+1]**2 - u[j]**2)/2*dx
        du = gmres(J,-F)[0]
        u = u + du
    return u

UM = EulerMethod(u0)
plt.plot(x,UM[:,ts])