Real inverse_stretch_strength () const {return inverse_stretch_strength_;}
Real inverse_compress_strength () const {return inverse_compress_strength_;}
Real blocking_force () const {return blocking_force_;}
Real inverse_stretch_strength () const {return inverse_stretch_strength_;}
Real inverse_compress_strength () const {return inverse_compress_strength_;}
Real blocking_force () const {return blocking_force_;}