docs: public static DMatrixRMaj nullspaceQR( DMatrixRMaj A , int totalSingular ) {
          SolveNullSpaceQR_DDRM solver = new SolveNullSpaceQR_DDRM();
  
          DMatrixRMaj nullspace = new DMatrixRMaj(1,1);
  
          if( !solver.process(A,totalSingular,nullspace))
              throw new RuntimeException("Solver failed. try SVD based method instead?");
  
          return nullspace;
      }