  The inversion problem for rational B\'ezier curves is addressed by using
resultant matrices for polynomials expressed in the Bernstein basis. The aim of
the work is not to construct an inversion formula but finding the corresponding
value of the parameter for each point on the curve. Since sometimes one has
only an approximation of that point the use of the singular value
decomposition, a key tool in numerical linear algebra, is shown to be adequate.
