Python中的 numpy.arccos()
numpy.arccos(x[, out]) = ufunc 'arccos') :此数学函数可帮助用户计算所有 x(作为数组元素)的反 cos。
参数 :
array : [array_like]elements are in radians.
out : [array_like]array of same shape as x.
Note :
2pi Radians = 360 degrees
The convention is to return the angle z whose real part lies in [0, pi].
返回 :
An array with inverse cosine of x
for all x i.e. array elements.
The values are in the closed interval [-pi/2, pi/2].
代码#1:工作
# Python program explaining
# arccos() function
import numpy as np
in_array = [0, 1, 0.3, -1]
print ("Input array : \n", in_array)
arccos_Values = np.arccos(in_array)
print ("\nInverse Cosine values : \n", arccos_Values)
输出 :
Input array :
[0, 1, 0.3, -1]
Inverse Cosine values :
[ 1.57079633 0. 1.26610367 3.14159265]
代码 #2:图形表示
# Python program showing
# Graphical representation
# of arccos() function
import numpy as np
import matplotlib.pyplot as plt
in_array = np.linspace(-np.pi, np.pi, 12)
out_array1 = np.cos(in_array)
out_array2 = np.arccos(in_array)
print("in_array : ", in_array)
print("\nout_array with cos : ", out_array1)
print("\nout_arraywith arccos : ", out_array1)
# red for numpy.arccos()
plt.plot(in_array, out_array1,
color = 'blue', marker = "*")
plt.plot(in_array, out_array2,
color = 'red', marker = "o")
plt.title("blue : numpy.cos() \nred : numpy.arccos()")
plt.xlabel("X")
plt.ylabel("Y")
plt.show()
输出 :
in_array : [-3.14159265 -2.57039399 -1.99919533 -1.42799666 -0.856798 -0.28559933
0.28559933 0.856798 1.42799666 1.99919533 2.57039399 3.14159265]
out_array with cos : [-1. -0.84125353 -0.41541501 0.14231484 0.65486073 0.95949297
0.95949297 0.65486073 0.14231484 -0.41541501 -0.84125353 -1. ]
out_arraywith arccos : [-1. -0.84125353 -0.41541501 0.14231484 0.65486073 0.95949297
0.95949297 0.65486073 0.14231484 -0.41541501 -0.84125353 -1. ]
RuntimeWarning: invalid value encountered in arccos
out_array1 = np.sin(in_array)
参考 :
https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.arcsin.html#numpy.arccos
.