如何绘制方程式

Question

如何绘制这些方程式？输出为空-只有轴但没有线

# taken from source code output of fitting software
a = -4.8044356996540731E+00
b = -1.7238982381056298E+00
c = 9.7121730188860766E+00
d = 2.0725836239688458E-02
f = -2.3810662793461059E+00
g = -6.8495593999129412E-05
h = 1.7294254445305737E-01
i = 2.6034147965619335E-02
j = -8.6126736653591163E-04
k = 5.8779369562417683E-05

z = a
z += b * x
z += c * y
z += d * pow(x, 2.0)
z += f * pow(y, 2.0)
z += g * pow(x, 3.0)
z += h* pow(y, 3.0)
z += i * x * y
z += j * pow(x, 2.0) * y
z += k * x * pow(y, 2.0)
return z

Answer 1

您当前正在计算x和y的单个值：

>>> import numpy as np
>>> r, a, n, t = 50, 5, 20, 5
>>> x = (r + a * np.sin(n * t * 360 )) * np.cos (t * 360 )
>>> y = (r + a * np.sin(n * t * 360 )) * np.sin (t * 360 )
>>> print(x, y)
-47.22961311822641 6.299155241288046

这意味着matplotlib没有行要绘制。

要绘制一条线，您必须传递两个或多个点，matplotlib才能在它们之间绘制线。

import matplotlib.pyplot as plt
import numpy as np

t = np.linspace(0, 2*np.pi, 100)  # create an array of 100 points between 0 and 2*pi
x = np.sin(2*t)
y = np.cos(t)

plt.plot(x, y)
plt.show()

或者您的情况：

t = np.linspace(0, 2*np.pi, 1000) 
# removed the factor *360 as numpy's sin/cos works with radians by default
x = (r + a * np.sin(n * t)) * np.cos(t) 
y = (r + a * np.sin(n * t)) * np.sin(t) 
plt.plot(x, y) 
plt.show()  

Answer 2

您正在t=5处评估函数。您应提供一系列值进行评估。例如，如果将t变量更改为

t= np.array([0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1])

您将看到一个图形。但是，您可以根据自己的需要定义范围和步骤