The averaging process for helix model computation.

In this example the first helical curve H₁₄ is computed using the first quadruple of backbone atoms {a₁,a₂,a₃,a₄}, the second curve H₂₅ the next quadruple of atoms {a₂,a₃,a₄,a₅} and so on. For a pair of two consecutive interior atoms up to three slightly different curves could be computed. The final model curve for the segment between a pair of consecutive atoms is their average (Eq 3).