set-global-staff-size integer only?

[Kieren Richard MacMillan]

[ Mac OS X 10.2.8 (Fink);  Lilypond 2.1.17-1 ]

Hey, everyone!

Does this work:

    #(set-global-staff-size 17.613)

or can you only choose integer point sizes? [I looked through the docs 
and couldn't find an explicit answer...)

Thanks,
Kieren.