"luma " <email@example.com> wrote in message <firstname.lastname@example.org>... > How could I specify the No.of bit that represent > for ex. > X=156.102 - - - - - - - - - It isn't clear what you are asking. In what connection do you need to "specify" bit lengths? Are you working with the Fixed Point Toolbox? It would require infinitely many binary bits to represent the number 156.102 exactly, so you would need to settle for an approximation; the more bits, the more accurate the approximation.