APL and nested arrays---a dream for statistical computation
Alan M. Sykes, Tom Stroud · ACM SIGAPL APL Quote Quad · 1997
F .L l O W c ' P o l y ' ( r X ) ( o 0 o ) ( ' L w i d t h ' 5) ( ' F s C y 1 e ' O ) ( ' F i I 1 c o l ' 255 0 O) Nested arrays play a crucial role here.Similarly, my use of nested arrays in APL programming has in the past generally only exploited nested array structures for passing complex arrays in and out of my user-defined functionsHowever, -most of statistics involves number crunching, calculating means and standard deviations etc., so this paper aims to show the reader that even in this specific area, numeric nested arrays are a gift to the statistician; a powerful tool waiting to be harnessed.Specifically, this paper looks only at numeric vectors or matrices, which have at least one scalar, which when disclosed, is itself a numeric vector and shows how scalar extension, e.g.+/1 2 3 (1 2 3) 7 8 9 A P L a n d Nested ~, , be exploited to great effect in database work where there are missing values which have been 'estimated' by the process of Multiple Imputation.