Feature: Check if matrix is nonnegative

[vprusso]

Provide a function that takes in as input a matrix (as a numpy array) and returns True if the matrix is nonnegative and False otherwise.

A function like the following could be written:

import numpy as np


def is_nonnegative(mat: np.ndarray) -> bool:
    """Check if a matrix is nonnegative.

    A matrix is nonnegative if all of the entries in the matrix are >= 0
    """
    return np.all(mat >= 0)

One would also need to provide proper documentation, examples, and unit tests for this function as well.