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);