Work on composite Basis for nonlinear mortaring

skfem/assembly/basis/abstract_basis.py

@@ -451,3 +451,23 @@ def draw(self, visuals='matplotlib', **kwargs):
             logger.warning("First argument, 'visuals', must be a string.")
         mod = importlib.import_module('skfem.visuals.{}'.format(visuals))
         return mod.draw(self, **kwargs)
+
+    def __mul__(self, other):
+        from copy import deepcopy
+        assert len(self.basis) == len(other.basis)
+        basis = []
+        element_dofs = []
+        for itr in range(len(self.basis)):
+            basis.append((self.basis[itr][0], other.basis[0][0].zeros()))
+            element_dofs.append(self.element_dofs[itr])
+        for itr in range(len(other.basis)):
+            basis.append((self.basis[0][0].zeros(), other.basis[itr][0]))
+            element_dofs.append(other.element_dofs[itr] + self.N)
+        out = deepcopy(self)
+        out.basis = basis
+        out.dofs.N = self.N + other.N
+        out.Nbfun = self.Nbfun + other.Nbfun
+        out._element_dofs = element_dofs
+        out.interpolate = lambda w: (self.interpolate(w[:self.N]),
+                                     other.interpolate(w[self.N:]))
+        return out