#######################
#      Functions      #
#######################

#A lot of functions in SPLUS are pre-written

x<-c(1:100)

sum(x) #Sum function
sqrt(x) #Square-root, element by element
log(x) #Natural log, element by element

#etc but it is also possible to write your own functions

#For example, for a function to take a matrix and produce a 
#vector of the row sums the following definition can be used

rowsum.func<-function(x){
	
	nr<-nrow(x) #nrow finds out how many rows x has
	svec<-numeric(length=nr)
	for(i in 1:nr){
		svec[i]<-sum(x[i,])
	}
	svec
	
}


xmat<-matrix(c(1:50),ncol=5,byrow=T)
rowsum.func(xmat)

#Actually, this operation can be implemented by using the "apply" function

apply(xmat,1,sum)

#This Worksheet has been completed