# Get the Trigonometric inverse cosine of the array elements in Python

The arccos is a multivalued function: for each x there are infinitely many numbers z such that cos(z) = x. The convention is to return the angle z whose real part lies in [0, pi]. The inverse cos is also known as acos or cos^-1.

For real-valued input data types, arccos always returns real output. For each value that cannot be expressed as a real number or infinity, it yields nan and sets the invalid floating point error flag. For complex-valued input, arccos is a complex analytic function that has branch cuts [-inf, -1] and [1, inf] and is continuous from above on the former and from below on the latter.

To find the Trigonometric inverse cosine of the array elements, use the numpy.arccos() method in Python Numpy. The method returns the angle of the array intersecting the unit circle at the given xcoordinate in radians [0, pi]. This is a scalar if x is a scalar.

The 1st parameter, x is the x-coordinate on the unit circle. For real arguments, the domain is [-1, 1], The 2nd and 3rd parameters are optional. The 2nd parameter is an ndarray, A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or None, a freshly-allocated array is returned.

The 3rd parameter is the condition is broadcast over the input. At locations where the condition is True, the out array will be set to the ufunc result. Elsewhere, the out array will retain its original value.

## Steps

At first, import the required library −

import numpy as np

Get the Trigonometric inverse cosine of the array elements. Array created using the numpy.array() method −

arr = np.array((1, -1, 0, 0.3))

Displaying our array −

print("Array...\n",arr)

Get the datatype −

print("\nArray datatype...\n",arr.dtype)


Get the dimensions of the Array −

print("\nArray Dimensions...\n",arr.ndim)

Get the number of elements of the Array −

print("\nNumber of elements in the Array...\n",arr.size)

Finding the Trigonometric inverse cosine of the array elements −

print("\nResult...",np.arccos(arr))

## Example

import numpy as np

# To find the Trigonometric inverse cosine of the array elements, use the numpy.arccos() method in Python Numpy
# The method returns the angle of the array intersecting the unit circle at the given x-coordinate in radians [0, pi]. This is a scalar if x is a scalar.
# The 1st parameter, x is the x-coordinate on the unit circle. For real arguments, the domain is [-1, 1].

print("Get the Trigonometric inverse cosine of the array elements...\n")

# Array created using the numpy.array() method
arr = np.array((1, -1, 0, 0.3))

# Display the array
print("Array...\n", arr)

# Get the type of the array
print("\nOur Array type...\n", arr.dtype)

# Get the dimensions of the Array
print("\nOur Array Dimensions...\n",arr.ndim)

# Get the number of elements in the Array
print("\nNumber of elements...\n", arr.size)

# Finding the Trigonometric inverse cosine of the array elements
print("\nResult...",np.arccos(arr))

## Output

Get the Trigonometric inverse cosine of the array elements...

Array...
[ 1. -1. 0. 0.3]

Our Array type...
float64

Our Array Dimensions...
1

Number of elements...
4

Result... [0. 3.14159265 1.57079633 1.26610367]