
^{(i−1)}
I, ^{(i−1)}
J, ^{(i)}
I and ^{(i)}
J are the coordinates of the nodes at the last (i − 1)th and the current (i)th configurations, respectively

^{(i−1)}yk is web plan vector of the element at the last configuration, perpendicular to the member axis
 φ_{k} is the rotation of the element about its axis (Table 6)

\({}^{(i  1)}\bar{y}_{k}\) is the position of ^{(i1)}y_{k} after performing the rotation φ_{k}

\({}^{(i)}\bar{y}_{k}\) is a web plan vector of the member at the current configuration, parallel to \({}^{(i  1)}\bar{y}_{k}\)

\({}^{(i)}y_{k}\) is the web plan vector of the current configuration that is \({}^{(i)}\bar{y}_{k}\) after normalizing (still in the web plan but perpendicular to the member axial axis)