Fix array sizing in PLU decomposition

README.md

@@ -6,7 +6,7 @@
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 </div>
 
 <div align=center>

docs/_templates/base.html

@@ -1,8 +1,8 @@
 {% extends "!base.html" %}
 
 {% block outdated %}
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- <a href="{{ '../' ~ base_url}}">
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-{% endblock %}
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+{% endblock %}

src/galois/_domains/_linalg.py

@@ -311,18 +311,18 @@ def __call__(self, A: Array) -> tuple[Array, Array]:
  if not A.ndim == 2:
  raise ValueError(f"Argument 'A' must be a 2-D matrix, not have shape {A.shape}.")
 
- n = A.shape[0]
+ m = A.shape[0]
  Ai = A.copy()
- L = self.field.Identity(n)
+ L = self.field.Identity(m)
 
- for i in range(0, n - 1):
+ for i in range(0, m - 1):
  if Ai[i, i] == 0:
  idxs = np.nonzero(Ai[i:, i])[0] # The first non-zero entry in column `i` below row `i`
  if idxs.size == 0: # pylint: disable=no-else-continue
  L[i, i] = 1
  continue
  else:
- raise ValueError("The LU decomposition of 'A' does not exist. Use the LUP decomposition instead.")
+ raise ValueError("The LU decomposition of 'A' does not exist. Use the PLU decomposition instead.")
 
  l = Ai[i + 1 :, i] / Ai[i, i]
  Ai[i + 1 :, :] -= np.multiply.outer(l, Ai[i, :])
@@ -343,13 +343,13 @@ def __call__(self, A: Array) -> tuple[Array, Array, Array, int]:
  if not A.ndim == 2:
  raise ValueError(f"Argument 'A' must be a 2-D matrix, not have shape {A.shape}.")
 
- n = A.shape[0]
+ m, n = A.shape
  Ai = A.copy()
- L = self.field.Zeros((n, n))
- P = self.field.Identity(n) # Row permutation matrix
+ L = self.field.Zeros((m, m))
+ P = self.field.Identity(m) # Row permutation matrix
  N_permutations = 0 # Number of permutations
 
- for i in range(0, n - 1):
+ for i in range(0, min(m, n)):
  if Ai[i, i] == 0:
  idxs = np.nonzero(Ai[i:, i])[0] # The first non-zero entry in column `i` below row `i`
  if idxs.size == 0:

tests/fields/test_linalg.py

@@ -369,6 +369,28 @@ def test_plu_decompose(field_plu_decompose):
  assert type(u) is GF
 
 
+def test_bug_476():
+ """
+ See https://github.com/mhostetter/galois/issues/476.
+ """
+ GF = galois.GF(2)
+ A = GF(
+ [
+ [1, 0, 0, 0, 0, 1],
+ [1, 1, 1, 1, 0, 1],
+ [1, 0, 0, 0, 0, 0],
+ [0, 1, 0, 0, 0, 0],
+ [0, 0, 1, 0, 0, 0],
+ [0, 0, 0, 1, 0, 0],
+ [0, 0, 0, 0, 1, 0],
+ [0, 0, 0, 0, 0, 1],
+ ]
+ )
+ P, L, U = A.plu_decompose()
+ PLU = P @ L @ U
+ assert np.array_equal(A, PLU)
+
+
 def test_matrix_inverse_exceptions():
  GF = galois.GF(2**8)
  with pytest.raises(np.linalg.LinAlgError):