docs: public static boolean isLowerTriangle(DMatrixRMaj A , int hessenberg , double tol ) {
          for( int i = 0; i < A.numRows-hessenberg-1; i++ ) {
              for( int j = i+hessenberg+1; j < A.numCols; j++ ) {
                  if( !(Math.abs(A.unsafe_get(i,j)) <= tol) ) {
                      return false;
                  }
              }
          }
          return true;
      }