Newsgroups: comp.lang.apl
Path: watmath!watserv2.uwaterloo.ca!torn!cs.utexas.edu!sun-barr!ames!agate!usenet.ins.cwru.edu!wariat!ppetto
From: ppetto@wariat.org (Peter J. Petto)
Subject: Empty Boxes as Null?
Message-ID: <1992Nov10.184152.27031@wariat.org>
Sender: ppetto@wariat.org
Organization: Akademia Pana Kleksa, Public Access Uni* Site
Date: Tue, 10 Nov 1992 18:41:52 GMT
Lines: 55

I'd been hoping that an empty box might be appropriately used to
represent a missing value in statistical calculations.  But I'm
getting some odd and unexpected results.  Here's a short example using
two vectors a and b -- the only difference is that b contains an
empty box in place of an average value.  Can anyone tell me why an
open empty box becomes 0 in this context, and why an open vector with
an empty box is of different rank than one without one?

My example:

      mean=. +/%#

      a
 +-+-+-+-+--+---+-+-+-+-+--+
 |3|4|5|8|12|6.4|3|4|5|8|12|
 +-+-+-+-+--+---+-+-+-+-+--+

      b
 +-+-+-+-+--++-+-+-+-+--+
 |3|4|5|8|12||3|4|5|8|12|
 +-+-+-+-+--++-+-+-+-+--+

      mean >a
 6.4

      mean >b
 5.81818

      >a
 3 4 5 8 12 6.4 3 4 5 8 12

      >b
  3
  4
  5
  8
 12
  0
  3
  4
  5
  8
 12

      $ >a
 11

      $ >b
 11 1

I'd appreciate any and all advice.

---
Peter Petto          |       ppetto@wariat.org
Bay Village, Ohio    |    73125.617@compuserve.com
