Self-starting nonlinear power law function

Dear all,

Has anyone written a self-starting power law function of the form

mypower=function(x,a,b,c){a+b*x^c}

?

Or is there a nonlinear regression package containing more selfStart() functions than nlme?

Thank you very much for your help!

Best wishes
Christoph

[running R 3.0.1 on Windows 7 32-Bit]