#作圓內接正N邊形 (python 程式碼)

#作圓內接正N邊形
import numpy as np
import matplotlib.pyplot as plt

R=10  #圓半徑
N=8   #正N邊形
a=0.3  #傾斜程度
plt.figure(figsize=(6,6),dpi=80)

#正N邊形的圖形
t = np.linspace(0+a,2*np.pi+a,N+1)
x=R*np.cos(t)
y=R*np.sin(t)
plt.plot(x,y,color="red",linewidth=5)

#圓的圖形
t = np.linspace(0,2*np.pi,100)
x=R*np.cos(t)
y=R*np.sin(t)
plt.plot(x,y,color="green",linewidth=3)

plt.show()

#Example

import matplotlib.pyplot as plt
from numpy import arange
from numpy import meshgrid
import numpy as np
np.seterr(divide='ignore', invalid='ignore')

xs = arange(-13,13, 0.1)
ys = arange(-13,13, 0.1)
x, y = meshgrid(xs, ys)

plt.figure(figsize=(12,12),dpi=80)
eq1 = abs(abs(x)-5)+abs(abs(y)-5)-6
eq2 = 4*x**2+9*y**2-400
eq3 = x**2-y**2-4
eq4 = x**6+y**6-1960000

plt.subplot(2,2,1)
plt.contour(x, y, eq1,[0],colors='red',linewidths=5)

plt.subplot(2,2,2)
plt.contour(x, y, eq2,[0],colors='blue',linewidths=5)

plt.subplot(2,2,3)
plt.contour(x, y, eq3,[0],colors='green',linewidths=5)

plt.subplot(2,2,4)
plt.contour(x, y, eq4,[0],colors='brown',linewidths=5)

plt.show()