### Special processors

After a singular point has been detected and located a singular point data structure will be created and initialized as described in section 3.2. If there are some special data (like eigenvalues) which may be of interest for a particular singular point then a call to `[failed,s] = feval(cds.curve_process,i,x,v,s)` should store this data in the `s.data` field. Here `i` indicates which singularity was detected and `x` and `v` are the point and tangent vector where this singularity was detected.