throws MatrixDimensionMismatchException { try { return subtract((BlockRealMatrix) m); } catch (ClassCastException cce) {
throws MatrixDimensionMismatchException { if (m instanceof BlockRealMatrix) { return subtract((BlockRealMatrix) m); } else {
throws MatrixDimensionMismatchException { try { return subtract((BlockRealMatrix) m); } catch (ClassCastException cce) {