python画函数图像-python实现画出e指数函数的图像

这里用Python逼近函数y = exp(x);同样使用泰勒函数去逼近:

exp(x) = 1 + x + (x)^2/(2!) + .. + (x)^n/(n!) + ...

#!/usr/bin/python

# -*- coding:utf-8 -*-

import numpy as np

import math

import matplotlib as mpl

import matplotlib.pyplot as plt

def calc_e_small(x):

n = 10

f = np.arange(1, n+1).cumprod()

b = np.array([x]*n).cumprod()

return np.sum(b / f) + 1

def calc_e(x):

reverse = False

if x < 0: # 处理负数

x = -x

reverse = True

ln2 = 0.69314718055994530941723212145818

c = x / ln2

a = int(c+0.5)

b = x - a*ln2

y = (2 ** a) * calc_e_small(b)

if reverse:

return 1/y

return y

if __name__ == "__main__":

t1 = np.linspace(-2, 0, 10, endpoint=False)

t2 = np.linspace(0, 3, 20)

t = np.concatenate((t1, t2))

print(t) # 横轴数据

y = np.empty_like(t)

for i, x in enumerate(t):

y[i] = calc_e(x)

p