makebasis

void  makebasis(vector &xaxis, vector &yaxis, vector zaxis)

void  makebasis(vector &xaxis, vector &yaxis, vector zaxis, vector u)

Completes an orthonormal basis for the given zaxis vector consisting of the xaxis and yaxis basis vectors. When only the zaxis vector is given, the basis will have an arbitrary orientation. When a second vector u is provided, the yaxis vector will be constrained so that it is aligned with that vector.