Lisp makes heavy use of functions. There are zillions of them, but once you know a few, you can write very compact code. Here are some examples of the arithmetic functions:

> (+ 1 4) 5 > (- 1 4) -3 > (* 1 4) 4 > (/ 1 4) 0.25 > (* 2 (/ 1 2)) 1.0Notice that the function is delineated by matching parenthesis and functions can be nested within functions.

For our work we need arrays of numbers. We could define them by hand as, e.g.,

> (def beach_gravity (list 22 34 30 24 55)) BEACH_GRAVITY > beach_gravity (22 34 30 24 55)Fortunately many of Lisp-Stat's functions are ``vectorized'', that is, they operate on entire arrays (or vectors). Thus

> (/ beach_gravity 2) (11 17 15 12 27.5)results in the division of each element of

`beach_gravity`

by 2. A slightly more interesting example, would be
> (- beach_gravity (mean beach_gravity)) (-11.0 1.0 -3.0 -9.0 22.0)Here we found the mean of the

`beach_gravity`

array,
and then subtracted this element-wise from the data.
Notice that we didn't have to tell the `mean`

function how many elements there were in `beach_gravity`

.

Tue Aug 29 09:10:30 MDT 1995