# [R] a strange problem with integrate()

vito muggeo vmuggeo at dssm.unipa.it
Wed Mar 1 18:27:43 CET 2006

```Dear all,
I am stuck on the following problem with integrate(). I have been out of
luck using RSiteSearch()..

My function is

g2<-function(b,theta,xi,yi,sigma2){
xi<-cbind(1,xi)
eta<-drop(xi%*%theta)
num<-exp((eta + rep(b,length(eta)))*yi)
den<- 1 + exp(eta + rep(b,length(eta)))
result=(num/den)*exp((-b^2)/sigma2)/sqrt(2*pi*sigma2)
r=prod(result)
return(r)
}

And I am interested in evaluating the simple integral, but:

> integrate(g2,-2,2,theta=c(-2,3),xi=c(1,2,5,6),yi=c(1,0,1,1),sigma2=1)
Error in integrate(g2, -2, 2, theta = c(-2, 3), xi = c(1, 2, 5, 6), yi =
c(1,  :
evaluation of function gave a result of wrong length
>

I have checked the integrand function

> valori<-seq(-2,2,l=30)
> risvalori<-NULL
> for(k in valori)
risvalori[length(risvalori)+1]<-g2(k,theta=c(-2,3),xi=c(1,2,5,6),yi=c(1,0,1,1),sigma2=1)
> plot(valori, risvalori)

And the integral exists..

Please, any comment is coming?

many thanks,
vito

--
====================================
Vito M.R. Muggeo
Dip.to Sc Statist e Matem `Vianelli'
Università di Palermo
viale delle Scienze, edificio 13
90128 Palermo - ITALY
tel: 091 6626240
fax: 091 485726/485612

```