Fix sparse construction for old scipy

629ysf · Apr 10, 2020 · c8671a5 · c8671a5
1 parent a35ec44
commit c8671a5
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/ddm/tridiag.py b/ddm/tridiag.py
@@ -72,7 +72,10 @@ def __init__(self, diag=None, up=None, down=None):
     @pns.returns(sparse.spmatrix)
     def to_scipy_sparse(self):
         """Returns the matrix as a scipy sparse matrix in CSR format."""
-        return sparse.diags([self.up, self.diag, self.down], [1, 0, -1], format="csr")
+        if len(self.up) == 0:
+            return sparse.diags([self.diag], [0])
+        else:
+            return sparse.diags([self.up, self.diag, self.down], [1, 0, -1], format="csr")
     @classmethod
     def eye(cls, size):
         """Return an identity matrix of size `size`."""