Compute the Outer Product of Two Given Vectors using NumPy in Python

The outer product of two vectors is a matrix where each element [i, j] is the product of the ith element of the first vector and the jth element of the second vector. NumPy provides the outer() function to calculate this efficiently.

Example: In this example, we calculate the outer product of two small 1D arrays.

import numpy as np x = np.array([1, 2]) y = np.array([3, 4]) res = np.outer(x, y) print(res) 

[[3 4] [6 8]] 

Explanation: np.outer(x, y) multiplies each element of x with each element of y to form a 2x2 matrix.

Syntax

numpy.outer(a, b, out=None)

Parameters:

• a: First input vector (1D array or flattened).
• b: Second input vector (1D array or flattened).
• out (Optional): array to store the result.

Returns: A 2D array where each element is a[i] * b[j].

Examples

Example 1: In this example, the outer product of two small arrays is calculated.

import numpy as np a = np.array([6, 2]) b = np.array([2, 5]) res = np.outer(a, b) print(res) 

[[12 30] [ 4 10]] 

Explanation: np.outer(a, b) multiplies each element of a with each element of b to form a 2x2 matrix.

Example 2: Here, two 2x2 matrices are flattened automatically and the outer product is computed.

import numpy as np a = np.array([[1, 3], [2, 6]]) b = np.array([[0, 1], [1, 9]]) res = np.outer(a, b) print(res) 

[[ 0 1 1 9] [ 0 3 3 27] [ 0 2 2 18] [ 0 6 6 54]] 

Explanation: np.outer(a, b) first flattens both matrices and then computes the outer product, producing a 4x4 matrix.

Example 3: In this example, two 3x3 matrices are flattened and their outer product is calculated.

import numpy as np a = np.array([[2, 8, 2], [3, 4, 8], [0, 2, 1]]) b = np.array([[2, 1, 1], [0, 1, 0], [2, 3, 0]]) res = np.outer(a, b) print(res) 

[[ 4 2 2 0 2 0 4 6 0] [16 8 8 0 8 0 16 24 0] [ 4 2 2 0 2 0 4 6 0] [ 6 3 3 0 3 0 6 9 0] [ 8 4 4 0 4 0 8 12 0] [16 8 8 0 8 0 16 24 0] [ 0 0 0 0 0 0 ...

Explanation: np.outer(a, b) flattens both 3x3 matrices into 1D arrays and calculates the outer product, resulting in a 9x9 matrix.