computeGq method
Computes G*q, where q are the generalized body coordinates
Implementation
double computeGq() {
final ga = jacobianElementA;
final gb = jacobianElementB;
final bi = this.bi;
final bj = this.bj;
final xi = bi.position;
final xj = bj.position;
return ga.spatial.dot(xi) + gb.spatial.dot(xj);
}