Last 2 dimensions of the array must be square

This error message typically occurs when you are trying to perform an operation on a multi-dimensional array where the last two dimensions are not equal in size. The error message is telling you that the last two dimensions of the array must be square, meaning that they must have the same number of rows and columns.

To fix this error, you need to reshape your array so that the last two dimensions are equal in size. One way to do this is to use the `reshape` method in NumPy. For example, if you have a 3-dimensional array with shape (3, 4, 6), you could reshape it to have the last two dimensions be square with the following code:

import numpy as np

# Create a 3-dimensional array
a = np.zeros((3, 4, 6))

# Reshape the array to have square last two dimensions
a = a.reshape((3, 2, 2, 3))

In this example, the original array has dimensions (3, 4, 6), but we reshape it to have dimensions (3, 2, 2, 3), which makes the last two dimensions square.