The `np.square()` function returns the element-wise square of its input:

``````import numpy as np

x = np.array([1, 2, 3])
np.square(x)

# Expected result
# array([1, 4, 9])
``````

The function accepts any array-like input. If the input is a scalar, it will return a scalar. If the input is an array, it will return an array. It will also convert Python sequences to `np.ndarray` if necessary.

But note: although similar in most cases, this operatoin is not exactly the same as `x ** 2`. When `x` is a `np.ndarray`, then `np.square()` is indeed equivalent to `x ** 2`, but when `x` is a `np.matrix`, then `x ** 2` will actually be the matrix multiplied by itself with matrix multiplication:

``````x_matrix = np.matrix(np.stack([x] * 3))
x_matrix

# Expected result
# matrix([[1, 2, 3],
#         [1, 2, 3],
#         [1, 2, 3]])

np.square(x_matrix)

# Expected result
# matrix([[1, 4, 9],
#         [1, 4, 9],
#         [1, 4, 9]])

x_matrix ** 2

# Expected result
# matrix([[ 6, 12, 18],
#         [ 6, 12, 18],
#         [ 6, 12, 18]])
``````

### A couple other notes about `np.square()`

• Data type will be left alone by the operation. If you input integer types you’ll get integer types out.
• It works on complex NumPy types.

If you want to know how to reverse the operation, check out my post on NumPy square root.