text: #include "bbd.h"
  
  void inv_Bk1dBk_Cpp(const int Bp1, const std::vector<double>& xvec, const mytype::ComplexVector& yvec, 
      mytype::ComplexVector& inv_Bk1dBk) {
  
  ////////////////////////
  // Compute Y_{k}/Y_{k-1}
  ////////////////////////
    
    mytype::ComplexNumber Dj = zero, Dj1 = zero;
      for (int j=0; j<Bp1; ++j) {
          Dj = yvec[j] + xvec[j]*Dj1;
          if (Dj == zero) Dj = tiny;
          Dj1 = one/Dj;
          inv_Bk1dBk[j] = Dj;
      }
  }
  