Fixing sum for python < 3.8

shenfun/la.py

@@ -36,7 +36,7 @@ def Solver(mats):
     mat = mats
     if isinstance(mats, list):
         bc_mats = extract_bc_matrices([mats])
-        mat = sum(mats[1:], start=mats[0])
+        mat = sum(mats[1:], mats[0])
     return mat.get_solver()([mat]+bc_mats)
 
 class SparseMatrixSolver:
@@ -58,7 +58,7 @@ def __init__(self, mat):
         self.bc_mats = []
         if isinstance(mat, list):
             bc_mats = extract_bc_matrices([mat])
-            mat = sum(mat[1:], start=mat[0])
+            mat = sum(mat[1:], mat[0])
             self.bc_mats = bc_mats
         self.mat = mat
         self._lu = None
@@ -972,7 +972,6 @@ def apply_constraint(A, b, offset, i, constraint):
                 return A, b
 
         row = offset + constraint[1]
-
         assert isinstance(constraint, tuple)
         assert len(constraint) == 3
         val = constraint[2]

shenfun/matrixbase.py

@@ -933,7 +933,7 @@ def diags(self, it=(0,), format='csr'):
                     bm[-1].append(d)
         return bmat(bm, format=format)
 
-    def solve(self, b, u=None, constraints=(), return_system=False, Alu=None, BM=None):
+    def solve(self, b, u=None, constraints=()):
         r"""
         Solve matrix system Au = b
 
@@ -971,19 +971,6 @@ def solve(self, b, u=None, constraints=(), return_system=False, Alu=None, BM=Non
             explicit boundary condition, like the pure Chebyshev or Legendre
             bases.
 
-        Other Parameters
-        ----------------
-        return_system : bool, optional
-            If True then return the assembled block matrix as well as the
-            solution in a 2-tuple (solution, matrix). This is helpful for
-            repeated solves, because the returned matrix may then be
-            factorized once and reused.
-            Only for non-periodic problems
-
-        Alu : pre-factorized matrix, optional
-            Computed with Alu = splu(self), where self is the assembled block
-            matrix. Only for non-periodic problems.
-
         """
         from .la import BlockMatrixSolver
         sol = BlockMatrixSolver(self)