[R] R loop help

[casperyc]

Hi,

I am tring to write a loop to compute this,
==========================
x1=c(
	rep(-1,4),
	rep(1,4)
	)

x2=c(
	rep(c(-1,-1,1,1),2)
	)
	
x3=c(
	rep(c(-1,1),4)
	)
	
x1*x2
x1*x3
x2*x3
========================

suppose i have x1,x2,x3
i want to compute their ' two factor interactions', x1x2,x1x3 and x2x3,
I wrote

========================
for(i in 1:2){
	for( j in i+1:3){
	xij=c()
	xij=xi*xj
	}
}
========================
it did not seem to recognize xi and xj

is there any suggestion?
it would be wonderful if there exists a single command that i can use

My ultimate aim is to find the 55 xixj s of the following data:
http://n4.nabble.com/file/n1692945/test_pic.jpg test_pic.jpg 


Thanks.
-- 
View this message in context: http://n4.nabble.com/R-loop-help-tp1692945p1692945.html
Sent from the R help mailing list archive at Nabble.com.