使用 3D function 的图形库

Question

hello

I need to use graphics library to draw the function
z=f(x,y)
when:
z=cos(r) * 0.1 ^ -r
and
r = sqrt ( x^2 + y^2)

I tried to write the code and got an error,Anyone know why?

from graphics import *
from math import *
def D3_graph(x,y,z,d):
    win = GraphWin("3D_graph",1000, 1000)
    win.setBackground(color_rgb(0,0,0))
    point =Circle(Point(500,500),300)
    for x_a in range(-7,7):
        sqrt_cul = sqrt((x-x_a)**2 + y**2)
        z=cos(sqrt_cul)*d**-(sqrt_cul)
        win.plot(x_a,y+z,"Blue") 
        win.plot(x_a,-y+z,"Blue")
    c.draw(win)
    win.getMouse()
    win.close()
D3_graph(300,300,100,0.1)

Answer 1

I believe that graphics.py (does not link to not the original file) is used in your project.

Some evident problems maybe

• When x, y = 300; d = 0.1, then d**-r will be 0.1^-424, which is larger than 1e+309 and thus float overflows. the magnitude of value is too large to be plotted.
• c.draw(win) but variable c is not declared before.

Other problems are

• I guess graphics.py is a 2D plot interface, not for 3D. And it is only usage is for teaching and demonstrating, not for complicated plotting.
• the range of x, y in [-300, 300] is too large. I think [-1.2, 1.2] is perhaps better.

I personally prefer a matplotlib workround. Code to plot this figure could be (also see matplotlib 3D surface tutorial )

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-1.15, 1.15, 300)
y = np.linspace(-1.15, 1.15, 300)
x, y = np.meshgrid(x, y)
r = np.sqrt(x**2 + y**2)
z = np.cos(r) * 0.1**-r

fig, ax = plt.subplots(subplot_kw={"projection": "3d"})
surf = ax.plot_surface(x, y, z)
fig.show()

The result figure could be