+ /* inv_hooke is the total flexibility of currently-active springs */
+ double inv_hooke = 0;
+ vsize i = sorted_springs.size ();
+ for ( ; i && sorted_springs[i - 1].blocking_force () < cur_force; i--)
+ inv_hooke += compressed
+ ? sorted_springs[i - 1].inverse_compress_strength ()
+ : sorted_springs[i - 1].inverse_stretch_strength ();
+ /* i now indexes the first active spring, so */
+ for ( ; i < sorted_springs.size (); i++)