Allow other name for FLEX preconditioner (#580)

* Allow other name for FLEX preconditioner

* Split generators for implicit and explicit preconditioners

Author: brownbaerchen

pySDC/core/sweeper.py

@@ -83,30 +83,27 @@ def __init__(self, params, level):
         self.__level = level
         self.parallelizable = False
 
-    def setupGenerator(self, qd_type):
+    def getGenerator(self, qd_type):
         coll = self.coll
-        try:
-            assert QDELTA_GENERATORS[qd_type] == type(self.generator)
-            assert self.generator.QDelta.shape[0] == coll.Qmat.shape[0] - 1
-        except (AssertionError, AttributeError):
-            self.generator = QDELTA_GENERATORS[qd_type](
-                # for algebraic types (LU, ...)
-                Q=coll.generator.Q,
-                # for MIN in tables, MIN-SR-S ...
-                nNodes=coll.num_nodes,
-                nodeType=coll.node_type,
-                quadType=coll.quad_type,
-                # for time-stepping types, MIN-SR-NS
-                nodes=coll.nodes,
-                tLeft=coll.tleft,
-            )
-        except Exception as e:
-            raise ValueError(f"could not generate {qd_type=!r} with qmat, got error : {e}") from e
+
+        generator = QDELTA_GENERATORS[qd_type](
+            # for algebraic types (LU, ...)
+            Q=coll.generator.Q,
+            # for MIN in tables, MIN-SR-S ...
+            nNodes=coll.num_nodes,
+            nodeType=coll.node_type,
+            quadType=coll.quad_type,
+            # for time-stepping types, MIN-SR-NS
+            nodes=coll.nodes,
+            tLeft=coll.tleft,
+        )
+
+        return generator
 
     def get_Qdelta_implicit(self, qd_type, k=None):
         QDmat = np.zeros_like(self.coll.Qmat)
-        self.setupGenerator(qd_type)
-        QDmat[1:, 1:] = self.generator.genCoeffs(k=k)
+        self.genQI = self.getGenerator(qd_type)
+        QDmat[1:, 1:] = self.genQI.genCoeffs(k=k)
 
         err_msg = 'Lower triangular matrix expected!'
         np.testing.assert_array_equal(np.triu(QDmat, k=1), np.zeros(QDmat.shape), err_msg=err_msg)
@@ -117,8 +114,8 @@ def get_Qdelta_implicit(self, qd_type, k=None):
     def get_Qdelta_explicit(self, qd_type, k=None):
         coll = self.coll
         QDmat = np.zeros(coll.Qmat.shape, dtype=float)
-        self.setupGenerator(qd_type)
-        QDmat[1:, 1:], QDmat[1:, 0] = self.generator.genCoeffs(k=k, dTau=True)
+        self.genQE = self.getGenerator(qd_type)
+        QDmat[1:, 1:], QDmat[1:, 0] = self.genQE.genCoeffs(k=k, dTau=True)
 
         err_msg = 'Strictly lower triangular matrix expected!'
         np.testing.assert_array_equal(np.triu(QDmat, k=0), np.zeros(QDmat.shape), err_msg=err_msg)
@@ -270,5 +267,5 @@ def updateVariableCoeffs(self, k):
         k : int
             Index of the sweep (0 for initial sweep, 1 for the first one, ...).
         """
-        if self.params.QI == 'MIN-SR-FLEX':
-            self.QI = self.get_Qdelta_implicit(qd_type="MIN-SR-FLEX", k=k)
+        if self.genQI._K_DEPENDENT:
+            self.QI = self.get_Qdelta_implicit(qd_type=self.genQI.__class__.__name__, k=k)