R help - Dec 2009 - Logarithm interpolation

Dear all, i want to know if in R exist a method that give a logarithm 
interpolation of a two columns of dates. I try to do the  lm of logarithm of 
the dates:

a<-lm(log(vettore)~log(as.numeric(pippo2[3,])))

but this is a 
linear correlation and not that i want.....

thanks

giuseppe