32 typedef Block<Derived> BlockXpr;  typedef
64 inline BlockXpr block(Index startRow, Index startCol, Index blockRows, Index blockCols)  in block()
66   return BlockXpr(derived(), startRow, startCol, blockRows, blockCols);  in block()
92 inline BlockXpr topRightCorner(Index cRows, Index cCols)  in topRightCorner()
94   return BlockXpr(derived(), 0, cols() - cCols, cRows, cCols);  in topRightCorner()
178 inline BlockXpr topLeftCorner(Index cRows, Index cCols)  in topLeftCorner()
180   return BlockXpr(derived(), 0, 0, cRows, cCols);  in topLeftCorner()
263 inline BlockXpr bottomRightCorner(Index cRows, Index cCols)  in bottomRightCorner()
265   return BlockXpr(derived(), rows() - cRows, cols() - cCols, cRows, cCols);  in bottomRightCorner()
348 inline BlockXpr bottomLeftCorner(Index cRows, Index cCols)  in bottomLeftCorner()
350   return BlockXpr(derived(), rows() - cRows, 0, cRows, cCols);  in bottomLeftCorner()