added check for matrix positive definiteness

burnman/utils/math.py

@@ -553,3 +553,16 @@ def generate_complete_basis(incomplete_basis, array):
  )
 
  return complete_basis.round(decimals=12) + 0.0
+
+
+def is_positive_definite(matrix):
+ """
+ Checks if a matrix is positive definite
+
+ :param matrix: Input matrix
+ :type matrix: 2D numpy array
+
+ :return: Whether or not the matrix is positive definite
+ :rtype: bool
+ """
+ return np.all(np.linalg.eigvals(matrix) > 0)

tests/test_tools.py

@@ -13,6 +13,7 @@
 from burnman.utils.math import smooth_array
 from burnman.utils.math import interp_smoothed_array_and_derivatives
 from burnman.utils.math import _pad_ndarray_inverse_mirror
+from burnman.utils.math import is_positive_definite
 
 
 class test_tools(BurnManTest):
@@ -200,6 +201,10 @@ def test_reactions_from_formulae(self):
  )
  self.assertTrue(R[0] == "2 fa = 2 fper + 1 fs")
 
+ def test_positive_definite(self):
+ arr = np.array([[2.0, 0.0], [0.0, 1.0]])
+ self.assertTrue(is_positive_definite(arr))
+
 
 if __name__ == "__main__":
  unittest.main()