Eliminate use of MultiCoordFunction._functions

src/sage/manifolds/continuous_map.py

@@ -2014,7 +2014,7 @@ def __invert__(self):
             # New symbolic variables (different from chart2._xx to allow for a
             #  correct solution even when chart2 = chart1):
             x2 = [SR.var('xxxx' + str(i)) for i in range(n2)]
-            equations = [x2[i] == coord_map._functions[i].expr()
+            equations = [x2[i] == coord_map[i].expr()
                          for i in range(n2)]
             solutions = solve(equations, chart1._xx, solution_dict=True)
             if not solutions:

src/sage/manifolds/differentiable/curve.py

@@ -539,7 +539,7 @@ def __call__(self, t, simplify=True):
         else:
             chart_pair = next(iter(self._coord_expression.keys()))
             # a chart is picked at random
-        coord_functions = self._coord_expression[chart_pair]._functions
+        coord_functions = self._coord_expression[chart_pair]
         n = codom._dim
         dict_subs = {canon_coord: t}
         coords = [coord_functions[i].expr().substitute(dict_subs)

src/sage/manifolds/scalarfield.py

@@ -1774,7 +1774,7 @@ def coord_function(self, chart=None, from_chart=None):
                                      "compute the expression in the {}".format(chart))
             change = self._domain._coord_changes[(chart, from_chart)]
             # old coordinates expressed in terms of the new ones:
-            coords = [ change._transf._functions[i].expr()
+            coords = [ change._transf[i].expr()
                        for i in range(self._manifold.dim()) ]
             new_expr = self._express[from_chart](*coords)
             self._express[chart] = chart.function(new_expr)