# How to Check if Eigenvalues are Positive in Python Using np.linalg.eigvals?

To check if eigenvalues are positive in Python using `np.linalg.eigvals` from the NumPy library, you can calculate the eigenvalues of a matrix and then check if all of them are greater than zero. Here’s an example:

``````import numpy as np

def check_positive_eigenvalues(matrix):
eigenvalues = np.linalg.eigvals(matrix)
return all(eigenvalues > 0)

# Example matrix
matrix = np.array([[1, 2], [3, 4]])

if check_positive_eigenvalues(matrix):
print("All eigenvalues are positive")
else:
print("Not all eigenvalues are positive")``````

In this example, we define a function `check_positive_eigenvalues` that takes a matrix as input. Inside the function, we calculate the eigenvalues of the matrix using `np.linalg.eigvals`. The function returns `True` if all eigenvalues are greater than zero (`eigenvalues > 0`), and `False` otherwise.

We then define an example matrix using the `np.array` function. You can replace `matrix` with your own matrix or create a function parameter to accept different matrices.

Finally, we call the `check_positive_eigenvalues` function with the `matrix` as the argument. If all eigenvalues of the matrix are positive, we print “All eigenvalues are positive”. Otherwise, if at least one eigenvalue is non-positive, we print “Not all eigenvalues are positive”.

Note that the `np.linalg.eigvals` function calculates all eigenvalues of a given matrix. If the matrix is large, this approach may be computationally expensive. In such cases, other techniques like matrix diagonalization or utilizing specific properties of the matrix may be more efficient.