From: Robert Klemme <shortcutter@...>
Date: 2009-01-31T19:00:04+09:00
Subject: Re: proper use of classes

On 31.01.2009 10:02, Tom Cloyd wrote:
> BTW, I was puzzled for years by the mathematical notion of a function. 
> It just eluded me. Baffled me. Then, as I was learning to program in 
> Fortran, years ago, I began to wonder if there was any relation between 
> Fortran functions (hope you know a little Fortran) and mathematical 
> functions. Of course, there is. Fortran functions was no problem at all 
> to grasp, and once I realized they were just another way of expressing a 
> mathematical function (or perhaps I should say that a math function can 
> be expressed as a Fortran function, and in fact that was what they were 
> for), I was seriously rageful.

IMHO there is an important distinction though which makes Fortran 
functions a bad example: mathematical functions usually do not have side 
effects, i.e. they can be completely described in terms of input and 
output.  I view them as a relationship (or call it a mapping) which 
assigns particular output values to particular input values.  If I'm not 
mistaken, a Fortran function can have side effects on arguments (and 
probably global variables).  A closer analogy are functions in - you 
guessed it - functional languages.

Kind regards

	robert