struct PK_TOPOL_fcstr_param_dp_s
       {
       PK_VECTOR_t du;
       PK_VECTOR_t dv;
       };
typedef struct PK_TOPOL_fcstr_param_dp_s
               PK_TOPOL_fcstr_param_dp_t;
struct PK_TOPOL_fctab_param_dp_s
       {
       PK_TOPOL_fcstr_param_dp_t *data;
       int                       length;
       };
typedef struct PK_TOPOL_fctab_param_dp_s  PK_TOPOL_fctab_param_dp_t;


This is a support structure for PK_TOPOL_facet_r_t. It represents
a two column table of du and dv first derivative surface values