# 作 y=A*sin(x)+B*cos(x)的函數圖形 (python 程式碼)

#題目：作 y=A*sin(x)+B*cos(x)的函數圖形

#Python 程式碼如下

# -*- coding: utf-8 -*-
import numpy as np
import matplotlib.pyplot as plt

A=4.0
B= -3.0

# 產生x座標的資料，從 -2PI 到 2PI
X = np.linspace(-2*np.pi, 2*np.pi, 1000, endpoint=True)

# Y座標
Sin_y = np.sin(X)
Cos_y = np.cos(X)
Ans_y = A*Sin_y+B*Cos_y

plt.figure(figsize=(12,9),dpi=80)

ax = plt.gca()  # gca stands for 'get current axis'
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
ax.xaxis.set_ticks_position('bottom')
ax.spines['bottom'].set_position(('data',0))
ax.yaxis.set_ticks_position('left')
ax.spines['left'].set_position(('data',0))

plt.plot(X, Sin_y, color="red", linewidth=2.0, linestyle=":", label="y=sin(x)")
plt.plot(X, Cos_y, color="green", linewidth=2.0, linestyle=":", label="y=cos(x)")
plt.plot(X, Ans_y, color="blue", linewidth=2.0, linestyle="-", label="y=A*sin(x)+B*cos(x)")

# 設定 x 座標文字
plt.xticks([-2*np.pi, -3*np.pi/2,-np.pi, -np.pi/2, 0, np.pi/2, np.pi, 3*np.pi/2,2*np.pi],
          [r'$-2\pi$', r'$-3\pi/2$',r'$-\pi$', r'$-\pi/2$', r'$0$', r'$+\pi/2$', r'$+\pi$', r'$3\pi/2$',r'$2\pi$'])


plt.legend(loc='upper right')

plt.show()

# 輸出結果如下: