numpy.arccos() in Python (original) (raw)

Last Updated : 08 Mar, 2024

numpy.arccos(x[, out]) = ufunc ‘arccos’) : This mathematical function helps user to calculate inverse cos for all x(being the array elements).

Parameters :

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].

Return :

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].

Code #1 : Working

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)

Output :

Input array : [0, 1, 0.3, -1]

Inverse Cosine values : [ 1.57079633 0. 1.26610367 3.14159265]

Code #2 : Graphical representation

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)

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()

Output :

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)

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