Write a MIX subroutine, to be used in connection with the other subroutines of this section, that calculates u @ 1, that is, u - [u] rounded to nearest floating point number, given a floating point number U. Note that when u is a very small negative number, u @ 1 will be rounded so that the result is unity (even though u mod 1 has been defined to be always less than unity, as a real number).