绘制 3D 矢量场

Question

我正在尝试绘制3D矢量场。我使用以下示例作为指导：

from mpl_toolkits.mplot3d import axes3d

import matplotlib.pyplot as plt

import numpy as np

fig = plt.figure()

ax = fig.gca(projection='3d')

x, y, z = np.meshgrid(np.arange(-0.8, 1, 0.2),

                      np.arange(-0.8, 1, 0.2),

                      np.arange(-0.8, 1, 0.8))

u = np.sin(np.pi * x) * np.cos(np.pi * y) * np.cos(np.pi * z)

v = -np.cos(np.pi * x) * np.sin(np.pi * y) * np.cos(np.pi * z)

w = (np.sqrt(2.0 / 3.0) * np.cos(np.pi * x) * np.cos(np.pi * y) *

     np.sin(np.pi * z))

ax.quiver(x, y, z, u, v, w, length=0.1)

plt.show()

此示例来自 matplotlib 示例库。但是，我想尝试使用其他函数来替换u，v和w，如下所示：

from mpl_toolkits.mplot3d import axes3d

import matplotlib.pyplot as plt

import numpy as np

fig = plt.figure()

ax = fig.gca(projection='3d')

x,y,z = np.meshgrid(np.arange(-0.1,0.005,0.1),np.arange(-0.1,0.005,0.1),np.arange(-0.1,0.005,0.1))

VolMag = 3.218E-6 #Volume of magnet in experiment in m^3

BR = np.sqrt(x**2 + y**2 + z**2)

MagMoment = np.array([0,0,(BInput*VolMag)/u0])

Bx = (u0/(4*np.pi))*(3*x*MagMoment*z)/BR**5

By = (u0/(4*np.pi))*(3*y*MagMoment*z)/BR**5

Bz = (u0/(4*np.pi))*((3*z*MagMoment*(z**2)/BR**5 - MagMoment/BR**3)

ax.quiver(x,y,z,Bx,By,Bz,length=0.1)

plt.show()

这给了我第16行的“无效语法”错误。这是为什么呢？我只更改了函数和定义的一些名称。

Answer 1

看起来你在这一行上缺少一个右括号。Bz = (u0/(4*np.pi))*((3*z*MagMoment*(z**2)/BR**5 - MagMoment/BR**3)应该是Bz = (u0/(4*np.pi))*((3*z*MagMoment*(z**2)/BR**5 - MagMoment/BR**3))