docs: @Override
      public boolean decompose( ZMatrixRMaj mat ) {
          if( mat.numRows != mat.numCols ) {
              throw new IllegalArgumentException("Must be a square matrix.");
          }
  
          n = mat.numRows;
  
          T = mat;
          t = T.data;
  
          if(lower) {
              return decomposeLower();
          } else {
              return decomposeUpper();
          }
      }