matplotlib函数积分图

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
def func(x):
return -(x-2)*(x-8)+40
x=np.linspace(0,10)
y=func(x)
fig,ax=plt.subplots()
plt.plot(x,y,‘r’,linewidth=2)
a = 2
b = 9
ax.set_xticks([a,b])
ax.set_yticks([])
ax.set_xticklabels([’$a$a’,’$b$b’])
ix=np.linspace(a,b)
iy=func(ix)
ixy=zip(ix,iy)
verts=[(a,0)]+list(ixy)+[(b,0)]
poly=Polygon(verts,facecolor=‘0.9’,edgecolor=‘0.5’)
ax.add_patch(poly)
plt.figtext(0.9,0.05,’$x$x’)
plt.figtext(0.1,0.9,’$y$y’)
x_math=(a+b)*0.5
y_math=35
plt.text(x_math,y_math,r’$\int_a^b (-(x-2)*(x-8)+40)dx$∫ab​(−(x−2)∗(x−8)+40)dx’,
fontsize=20,horizontalalignment=‘center’)
plt.show()