message: New method UpdateConstants in class PWConstCoefficient
diff: @@ -85,6 +85,9 @@ public:
  PWConstCoefficient(Vector &c)
  { constants.SetSize(c.Size()); constants=c; }
  + /// Update constants
  + void UpdateConstants(Vector &c) {constants.SetSize(c.Size()); constants=c;}
  +
  /// Member function to access or modify the value of the i-th constant
  double &operator()(int i) { return constants(i-1); }
  