30 void svd22(
const double A[4], 
double U[4], 
double S[2], 
double V[4]);
    34                              double *Lmin, 
double *Lmax);
 void svd_sym_singular_values(double A00, double A01, double A11, double *Lmin, double *Lmax)
void svd22(const double A[4], double U[4], double S[2], double V[4])