Finally print out your own personal edition of Pascal's Triangle or those Stirling numbers of second kind that you've always wanted! Whack 'em down any way you want! Draw little bubbles that look neat, even if you don't really understand them!

This is tkrec, a combination of scheme, PostScript, perl, and tcl[Tk] code that can be fun and useful (or something).

Here's an example portion of concentric circles, each corresponding to the highest power of 5 that divides the Stirling number of the second kind which corresponds to that place.
[weirdo circles]

Working with it

You need some scheme (preferably a newer version of Aubrey Jaffer's scm, as older ones had a nasty modulo bug), Tk4.0+, some kind of Perl (although you could easily hack up npscvt to use sh or something), and something with which you can view PostScript.

The interface is kind of a Monty the Amazing Weatherman, but it's all pretty straightforward:

[screen shot]

Here, we're all set to view rows 22-80 of the Eulerian numbers, in landscape mode, and each place will show the highest power of 3 which divides the Eulerian number which would be in that place. A PostScript file called "foo" will be created when you click on `Calc,' and `Preview' will run ghostview on whatever happens to be in "foo." `Print' follows in the same way.

There is a whole slew of ways you can view things, just try it out.

So try it out

Here is the code. It's all rather straightforward, but email me if you get lost. If you want a new feature, please also let me know.

$Id: index.php,v 1.4 2000/09/07 23:10:32 bri Exp $