docs: public static boolean isUpperTriangle(ZMatrixRMaj A , int hessenberg , double tol ) {
          tol *= tol;
          for( int i = hessenberg+1; i < A.numRows; i++ ) {
              int maxCol = Math.min(i-hessenberg, A.numCols);
              for( int j = 0; j < maxCol; j++ ) {
                  int index = (i*A.numCols+j)*2;
  
                  double real = A.data[index];
                  double imag = A.data[index+1];
                  double mag = real*real + imag*imag;
  
                  if( !(mag <= tol) ) {
                      return false;
                  }
              }
          }
          return true;
      }