[R] Fitting to strange function

[JB]

At 13.11.2003 (17:17), Roger D. Peng wrote:
>You could use nls() or optimize().
>
>-roger

Well, thx.
This is very complicated. In Mupad I simply say:

         r:=stats::reg(t_list,x_list,a/2*t^2+sqrt(0.08*a)*t,[t],[a])

and get the (right) answer. How would the same command in R go?

TIA,

jb