/// mark column #i# as being loose.
void loosen_column (int i);
/// the index of #c# in #cols#
/// mark column #i# as being loose.
void loosen_column (int i);
/// the index of #c# in #cols#
/// make the energy function
void make_matrices (Matrix &quad, Vector &lin,Real&) const;
/// make the energy function
void make_matrices (Matrix &quad, Vector &lin,Real&) const;