What is R and why does it have such a silly name?
	what the encyclopedia says
	descended from S, developed at Bell Labs (home of C)
	S was developed by John Chambers, described in several books
R is an implementation of S 
	so is S-Plus (a commercial product)
	the two are very similar
	we have a site license for S-plus and you could use it identically
	I'll mention the few differences between R and S-plus as we come to them
Why (not) use R
	+very powerful computing environment for data analysis
	+under active development by enthusiastic volunteers
	+lots of specialised software packages available
	+you can distribute your own code 
	+superb graphics capabilities
	-hard to get started
	-documentation style requires getting used to
	-aimed at statisticians
Why (not) use S+
	+very powerful computing environment for data analysis
	+under active development by a company
	+lots of specialised software packages available
	+superb graphics capabilities
	+some help in getting started from menus
	-you can distribute your own code but ithers need S+ to use it
	-R packages will probably run but need to be ported
What are the characteristics of R
	command line interface similar to unix shell 
		vaguely C - like syntax
		command-line editing
		online help in man-page tradition
	programming environment designed for interactive use
	functional programming language similar to scheme 
	object oriented features
	high and low level graphics
Installation of R
	http://www.r-project.org/
	http://www.stats.bris.ac.uk/R/

Functions
	functions are the only way of making something happen
	name(args)
	easy to define your own:
		myfu <- function (a,b) {a+b}
	args may not be required but () are always required 
		sum(1,2)
		q() # quit R
		q   # print q function
	the basic arithmetic operators are convenience exceptions
		'+'(1,2)
		1+2
	

Playing with R: basic arithmetic
	if you type in an expression R will evaluate and print-
	5*2 
	5^2
	100%%3
	100%/%3
	multiply and divide come before add and subtract

vectorise me!
	variable names start with a letter
	assign values to variable names with <-
	basic data structure is the vector
	a <- 1:100
	b <- c(1,0)   # c is a function that combines its arguments
	all of the basic functions work on vectors 
	a + 0.5
	a + a
recycling
	operations on vectors of unequal length recycle the shorter one
	a <- 1:100
	b <- c(1,0)
	a + b # add 1 to odd numbered positions only
indexing: index vectors
	a[50]      # 50
	a[-50]     # everything but 50
	a[100:1]   # backwards
	a[c(1:100,100:1)] # count down then up
	a[1:10*10] # every tenth number

indexing: logical vectors
	b <- a%%2==1
	a[b] # odd only
	
Exercises:  
	calculate the sum of odd numbers up to 1000
	what's the largest multiple of 13 under 1000
	calculate pi using the Gregory-Leibniz series