void C_LinearStatistic(const double *x, const int p,

                       const double *y, const int q,

                       const double *weights, const int n,

                       double *ans);

void C_ExpectCovarInfluence(const double* y, const int q,

                            const double* weights, const int n,

                            SEXP ans);

void C_ExpectCovarLinearStatistic(const double* x, const int p,

                                  const double* y, const int q,

                                  const double* weights, const int n,

                                  const SEXP expcovinf, SEXP ans);

void C_PermutedLinearStatistic(const double *x, const int p,

                               const double *y, const int q,

                               const int n, const int nperm,

                               const int *indx, const int *perm,

                               double *ans);

SEXP R_ExpectCovarInfluence(SEXP y, SEXP weights);