Minor fix to breakdown.

src/afgl/util/lanczos.py

@@ -1,6 +1,8 @@
 import numpy as np
 import numpy.linalg as LA
 
+
+def lanczos(L, s, M):
     """
     Classic Lanczos method (without re-orthogonalization)
 
@@ -18,9 +20,6 @@ alp : ndarray
     beta : ndarray
         M-dimensional array of scalars.
     """
-
-
-def lanczos(L, s, M):
     N = len(s)
     alp = np.zeros(M)
     beta = np.zeros(M - 1)
@@ -37,8 +36,9 @@ def lanczos(L, s, M):
 
         if j < M - 1:
             beta[j] = LA.norm(w)
-            if beta[j] == 0:
-                break
+            if beta[j] < 1e-14:
+                print("BREAKDOWN")
+                return V[:, : j + 1], alp[: j + 1], beta[:j]
             V[:, j + 1] = w / beta[j]
 
-    return [V, alp, beta]
+    return V, alp, beta