On Fri, Oct 11, 2013 at 08:49:44PM -0400, [email protected] wrote: > > Most recently, I've been going through the same exercise > (again for a chapter, now not in a book of my own) for > "recursion" and "recursive". Again, I have accumulated
... what a mess! Back in the day when I was teaching computational science for a living, I had to carefully explain the difference between two distinct meanings of recursion. 1) A "recursive loop" is one whose iterations depend on values computed in the previous loop. Related obviously to the "oldest" mathematical definition you gave. It impedes vectorisation and parallelisation of said loop. 2) A "recursive function" is one that calls itself, a term quite familiar to people brought up in computer science. In the good old days, when men programmed in Fortran, concept 1 was always meant, as Fortran did not support recursion. That has all changed now :). And there is a third meaning for recursion used by theoretical computer scientists, where is basically means a computable function. See page 29 of Li and Vitanyi's tome of Kolmogorov complexity. Cheers - ---------------------------------------------------------------------------- Prof Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Professor of Mathematics [email protected] University of New South Wales http://www.hpcoders.com.au ---------------------------------------------------------------------------- ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
