[R] avoiding loops in equation

[Julius Tesoro]

To illustrate my problem, I have a complex code of several matrices and a vector. To simplify I only used two matrices and a vector as an example:

pex<-function(acc, pga, std){
  (acc-pga)/std
}

acc<-seq(.1,1,.1)
pga<-matrix(rnorm(9,4,.1),3,3)
std<-matrix(rnorm(9,4,.5),3,3)

I tried calculating the above function for each element of acc using:

	for (x in 1:length(acc)){
		a1<-pex(acc[x],pga,std)
		if(x==1){a2<-a1
			}else {a2<-rbind(a2,a1)

	}

I want to recode the following using sapply 

	a2<-sapply(acc, function(x) pex(x,pga,std))

but what I get is a different result.

Anyone knows how to rewrite the above function without using loops?

Thanks everyone.