Notes Folio n010207 What's an Algorithm?

miser>notes> 2001>02> n010207> 0.00 2017-08-29 16:40

It is too commonplace to assume that computer programs are the same as algorithms.  Not every procedure specified by a computer program is necessarily an algorithm.  Indeed, all manner of procedures, whether involving computers or not, fail to be algorithms.

To limit algorithm-hood to computer programs captures the essence of an algorithm at an inappropriate level.  Algorithms are found in more places than that and they tend to be more abstract than computer code.

In the view employed here, there are many ways to instantiate a particular algorithm in computer code while preserving the essential nature of the algorithm. 

An important distinction that I tend to promote is the following:

1. There is some functional relationship that the algorithm is intended to implement by computation, possibly with practical constraints and limits.

2. Part of the specification of an algorithm includes demonstration that the specified functional relationship is actually achieved.

Put another way, for an algorithm to be established, it is essential to know what the algorithm is for and how is it known that the algorithm accomplishes that purpose. 

There are other characteristics that an algorithm also must have, many of them being well-established long before there were practical means of implementing them with digital computers, rather than (in principle) pencil and paper.

Here, algorithm will be defined to reflect the historical understanding of algorithm along with the importance of knowing what the algorithm is for.

-- Dennis E. Hamilton
Seattle, Washington
2014-04-03

Related Material

• n010207b: What's an Algorithm [latest]

• n010207c: Initial Notes

• n010207a: Diary & Job Jar
    

• n020201: Manifest Abstractions

• n020202: Homage to the Bit

• n020205: Programs Are Rarely Algorithms

• n020207: What's an Algorithm?

History

0.02 2014-04-03-18:37 Transpose to Folio Cover Page

The previous comment is preserved as Initial Notes and this page is adjusted to provide a folio cover page for what is here and what is to follow.

0.01 2006-06-08-18:44 Correct Folio Number

The page said N020207, but the catalog has N010207 and that appears to be reliable.  However, this is when I created the catalog entry, not when I actually moved the initial content here from Orcmid's Lair and the commentary on Sedwick.  This will be improved when the folio is reconstructed under Astraendo, where this question is more applicable.

0.00 2002-12-07-22:51 Split off from Orcmid Reading R010101a to provide initial material (orcmid).

The original too-comprehensive note is pasted here as a boilerplate to be distilled down to the basic What Is An Algorithm discussion.  Beside my critique of Sedgwick, I want to add Knuth (from several sources), Brookshear, and others who have provided sharpening of the fundamental idea of an algorithm.

 

---

You are navigating the Miser Project.

created 2002-12-07-22:51 -0800 (pst) by orcmid $$Author: Orcmid $ $$Date: 17-08-29 16:40 $ $$Revision: 20 $