[R] Circular variables within a GLM, GLM-GEE or GAM

[Clare Embling]

Hi,

I have a variable (current speed direction) which is circular (0=360 degrees), and I'd like my GLM to include the variable as a circular variable.  Can I do this?  And what is the code?

I'm actually doing a GLM-GEE using the 'geepack' package, so want to use it in that, but also interested in whether it can also be used in GLMs and GAMs (I use the 'mgcv' package for GAMs).

Any help would be gratefully received,
Thanks in advance,
:o) Clare