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Introduction
To R

Simple R Arithmetic

You can use R to evaluate some simple expressions. For example: 
> 1+2+3          Let's add these
[1] 6            the answer, labelled with a [1]

> 2+3*4          Slightly more complex...
[1] 14           multiplication is done first

> 3/2+1
[1] 2.5          as is division

> 4*3**3         Use ** or ^ for powers.
[1] 108          and powers are done before * and /
[The [1] looks a bit odd but its function will be clear later!]

R also provides the sort of functions you find on a calculator: 

> sqrt(2)
[1] 1.414214

> sin(3.14159)      sin(Pi radians) is zero
[1] 2.65359e-06      and this is close...
It also provides Pi as a constant. Try this: 
> sin(pi)
[1] 1.224606e-16     much closer to zero...
Here's a short list of some of the arithmetic functions in R:
Name Operation
sqrt square root
abs absolute (positive) value
sin cos tan trig functions 
asin acos atan  inverse trig functions 
sinh cosh tanh  hyperbolic functions 
asinh acosh atanh  inverse hyperbolic functions 
exp log  exponential and natural logarithm 
log10  base-10 log 
gamma lgamma  gamma function and its natural log 
These functions can be nested and combined to make more complex expressions: 
> sqrt(sin(45*pi/180))
[1] 0.8408964
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