python画函数等高图

函数等高图"/>

python画函数等高图

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)

print('e^', x, ' = ', y[i], '(近似值)\t', math.exp(x), '(真实值)')

print '误差：', y[i] - math.exp(x)

plt.figure(facecolor='w')

mpl.rcParams['font.sans-serif'] = [u'SimHei']

mpl.rcParams['axes.unicode_minus'] = False

plt.plot(t, y, 'r-', t, y, 'go', linewidth=2)

plt.title(u'Taylor展式的应用 - 指数函数', fontsize=18)

plt.xlabel('X', fontsize=15)

plt.ylabel('exp(X)', fontsize=15)

plt.grid(True)

plt.show()