The input arguments odefile, xnew, p, ap are built exactly as in
init_LP_LP. The output vector x0 consists of extended with the free parameters and paramter
from (62).
MATCONT provides four other initializers which allow to continue a Hopf curve by starting from a codim 2 equilibrium point. These are init_BT_H.m, init_GH_H.m, init_HH_H.m and init_ZH_H.m These initializers are added merely for ease of use since they refer back to init_H_H.m. However, we note that two Hopf curves pass through a Hopf point. So it can be necessary to specify the tangent vector to the desired Hopf curve.