Skip coefficient if its value is 1 (or near 1)

Change-Id: I39a5630cc76250ded1ab22709522344d42fcc0e9
Reviewed-on: https://gerrit.libreoffice.org/19037Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>