[R] Problem with 'expression'

[Perez Martin, Agustin]

DeaR useRs:

Excuses by my English.
I have a problem with 'expression' function.

For example:

	a<-expression(exp(-x^2))
	b<-expression(exp(x^2))

And I want to calculate:

	a*b

And R returns:

	Error in a * b : non-numeric argument to binary operator

I don't know what happend.
Which is the way to making operations with expressions?
Thanks.