[R] show numbers not rounded

[Christoph Lehmann]

how can I show an number not rounded, but in the format, eg. x.xxxx 

e.g. 
> signif(1-pf(((RSSred-RSSful)/2)/(RSSful/(34-3)),2,34-3),digits = 5)

shows
[1] 0

but I need something like

[1] 2.2e-16


thanks
christoph
-- 
Christoph Lehmann                            Phone:  ++41 31 930 93 83 
Department of Psychiatric Neurophysiology    Mobile: ++41 76 570 28 00
University Hospital of Clinical Psychiatry   Fax:    ++41 31 930 99 61 
Waldau                                            lehmann at puk.unibe.ch 
CH-3000 Bern 60            http://www.puk.unibe.ch/cl/pn_ni_cv_cl.html