Complex integration in R

Dear R-user

I need a function to approximate a complex integration. My function is:

aprox2=function(s,x,rate){
    dexp(x,rate)*exp(-s*x)
}

where argument s is a complex number. I can't use the integrate function
because it's only used with "numeric" arguments

Does anyone know some function to approximate complex integrals?

Thanks
Borja

	[[alternative HTML version deleted]]