import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0, 10, 100)
y = x**2
#Left-hand estimate
rect_x = np.linspace(0, 10, 11)
rect_y = rect_x**2
rect_height = rect_y[:-1]
rect_width = rect_x[1:] - rect_x[:-1]
#Right-hand estimate
rect_x_r = np.linspace(-1, 9, 11)
rect_y_r = (rect_x_r+1)**2
rect_height_r = rect_y_r[1:]
rect_width_r = rect_x_r[1:] - rect_x_r[:-1]
plt.bar(rect_x_r[1:], rect_height_r, rect_width_r, align='edge', alpha=0.5, color='orange', label='Right-hand estimate')
plt.bar(rect_x[:-1], rect_height, rect_width, align='edge', alpha=0.5, color='blue', label='Left-hand estimate')
plt.plot(x, y, label='y = x^2')
plt.xlabel('x')
plt.ylabel('y')
plt.title('y = x^2 and Left/Right-hand estimate')
plt.legend()
plt.grid()
plt.show()
氦的發現與回收 氦是 1868 年天文學家觀測日食時的太陽光譜線時，意外發現的新元素，以太陽神 Helios 命名為 Helium ，也能突顯氦元素發現的曲折歷史。 氦元素質量比大氣主要氣體分子氮和氧輕很多，只要從石油或岩層溢出，就能輕易的飄到地球大氣層上方。雖然只有少數地表...