python math.log对数

对数函数

import math
import matplotlib.pyplot as plt
import numpy as np

if __name__ == '__main__':
    x = np.arange(0.05,3,0.05)
    y1 = [math.log(a,1.5) for a in x]
    plt.plot(x,y1,linewidth=2,color='red',label ='log1.5(x)')
    print(y1)
    plt.plot([1,1],[y1[0],y1[-1]],"r--",linewidth=2)
    y2 = [math.log(a, 2) for a in x]
    plt.plot(x, y2, linewidth=2, color='green', label='log2(x)')
    y3 = [math.log(a, 3) for a in x]
    plt.plot(x, y3, linewidth=2, color='blue', label='log3(x)')
    plt.legend(loc='lower right')
    plt.grid(True)
    plt.show()

如果a的x次方=N（a>0，且a≠1），

那么数x叫做以a为底N的对数，记作x=logaN，读作以a为底N的对数，其中a叫做对数的底数，N叫做真数