docs: static void backsubstitution0134(DMatrixRMaj P_plus, DMatrixRMaj P , DMatrixRMaj X ,
  									 double H[] ) {
  		final int N = P.numRows;
  		DMatrixRMaj tmp = new DMatrixRMaj(N*2, 1);
  
  		double H6 = H[6];
  		double H7 = H[7];
  		double H8 = H[8];
  
  		for (int i = 0, index = 0; i < N; i++) {
  			double x = -X.data[index],y = -X.data[index+1];
  			double sum = P.data[index++] * H6 + P.data[index++] * H7 + H8;
  			tmp.data[i] = x * sum;
  			tmp.data[i+N] = y * sum;
  		}
  
  		double h0=0,h1=0,h3=0,h4=0;
  		for (int i = 0; i < N; i++) {
  			double P_pls_0 = P_plus.data[i];
  			double P_pls_1 = P_plus.data[i+N];
  
  			double tmp_i = tmp.data[i];
  			double tmp_j = tmp.data[i+N];
  
  			h0 += P_pls_0*tmp_i;
  			h1 += P_pls_1*tmp_i;
  			h3 += P_pls_0*tmp_j;
  			h4 += P_pls_1*tmp_j;
  		}
  
  		H[0] = -h0;
  		H[1] = -h1;
  		H[3] = -h3;
  		H[4] = -h4;
  	}