Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!ubc-vision!fornax!zeke
From: zeke@fornax.UUCP (Zeke Hoskin)
Newsgroups: comp.lang.apl
Subject: mode
Message-ID: <455@fornax.UUCP>
Date: 29 Feb 88 18:20:32 GMT
Lines: 12
Keywords: outer product

The nice thing about outer-product-based mode is that
it lends itself to a one-liner which you can print on
a T shirt and tell people you are dressed in the latest
mode. I guess a shirt is an outer product in its own 
right....
   The bad evil nasty thing is that it is an O(Nsquared)
algorithm. Here is a faster one:
   X <- X[gradeup X <- ,X]
   bool <- X =/= 1 drop X,somevalueotherthangreatestX
   ends <- bool / iota rho bool
   lengths <- ends - minus1 drop 0, ends  (in origin 1)
   pos <- ends [ lengths iota gratest reduc lengths]
   mode <- X[pos]