[R] integrate / Vectorize question

[Gerrit Draisma]

Dear R-users,

I want to use the function Fnum below
in another integrate procedure.

How do I write Fnum so that it returns a vector of values?
And will the last integrate return the right answer?

(I tried Vectorize() in several places,
but got all sorts of errors.)

Thanks for helping out.

Gerrit.


This my code
=========================
beta=c(3,0.3)*1E-2
mu<-5

f<-function(x,beta){beta[1]+beta[2]*x}

Fnum<-function(x,beta){
    integrate(f,lower=-x,upper=0,beta=beta)$value
    }

Fsym<-function(x,beta){x*(beta[1]-beta[2]/2*x)}

y<-1:4
Fsym(y,beta)
Fnum(y,beta)

g<-function(y,mu){exp(-y/mu)/mu}

integrate((function(y,beta,mu){Fsym(y,beta)*g(y,mu)}),lower=0,upper=2*mu,
   beta=beta,mu=mu)

#This fails
integrate((function(y,beta,mu){Fnum(y,beta)*g(y,mu)}),lower=0,upper=2*mu,
   beta=beta,mu=mu)

t<-seq(0,2*mu, by=0.2)
0.2*sum(tapply(t,t,function(y,beta,mu){Fnum(y,beta)*g(y,mu)},
    beta=beta,mu=mu))