[R] Find the functional relationship between two variables in R?

[jtang at mappi.helsinki.fi]

Hi,
I have two variables x and y and the functional relationship between x  
and y is like: y=x^2+log(x). My question is that is it possible to  
apply some method to reconstruct the functional form based on the  
training data that is generated from it? I understand that there are  
many methods for regresstion but none of them can predict the  
functions that consist of operators.

For example in R:
x=seq(1:100)
y=x^2+log(x)
result=somemodel(x,y)
summary(result)
The output of the method is ideally a mathematical equation that fits  
to the training data, e.g.
>> y=x^2+log(x)

Any ideas will be appreciated!
Best,
Jing