Listing and Undefining Variables

After you have been working for a while you may want to find out what variables you have defined (using def ). The function variables   will produce a listing:

> (variables)
CO
HC
RURAL
URBAN
PRECIPITATION
PURCHASES
NIL
>

If you are working on a 1Mb Macintosh you may occasionally want to free up some space by getting rid of some variables you no longer need. You can do this using the undef   function:

> (undef 'co)
CO
> (variables)
HC
RURAL
URBAN
PRECIPITATION
PURCHASES
NIL
>