`to_rational`

Here's how:

        to_rational() {
          # Crapulent bash can't handle decimal numbers, so we will convert
          # the input number to a rational
          if [[ $1 =~ (.*)\.(.*) ]] ; then
              i_part=${BASH_REMATCH[1]}
              f_part=${BASH_REMATCH[2]}
              n="$i_part$f_part";
              d=$(( 10 ** ${#f_part} ))
          else
              n=$1
              d=1
          fi
        }

For example, 2.45 results in n=245, d=100