<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV>Hi Folks,</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Thanks to everyone who replied to my earlier email. I have not resolved the problem fully , but here's an interim response...</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Thanks to Andrew Savage for pointing me to <A href="http://www.oreilly.com/catalog/perlbp/chapter/index.html">http://www.oreilly.com/catalog/perlbp/chapter/index.html</A> . Being new to Perl (in fact to any modern programming language), this is the kind of thing I need to get acquainted with. Indeed, establishing a 'best practice', or 'this is how we do it' approach is very important to my project because I want it to be 'hackable' by other engineers in my profession, and they have even less understanding of Perl than me ( I had better add that I want to make the calculations explicit for future interrogation and reference, rather than hiding them away in a compiled program, so even if my colleagues will not understand subs, refs and the like, they can at least see that 1 + 1 = 2).</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Thanks to the tip about $a. I was trying to avoid $variables_with_really_long_names, but at least $variables_with_really_long_names tell you what they are, and there's little likelihood of confusing them with something that refers to something else.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Some of you suggested I include some of the code. In future I will but, to be honest, it looks pretty horrible at the moment because of my rudimentary (but improving) knowledge of Perl. If I told you I am only just beginning to understand references and regexes, you will probably understand what I mean.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>With regard to prototypes, I had started using them on the advice of a friend of mine, who is a Perl geek. I don't have the experience to argue the pros and cons, but I am willing to follow the advice in Perl Best Practice (which is what I need to get to grips with in any case).</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Back to the drawing board...</DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Lucida Grande; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Lucida Grande; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Lucida Grande; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV>Regards,</DIV><DIV>Martin</DIV><DIV>Visit my website...</DIV><DIV><A href="http://web.mac.com/martin_jacobs1"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 238); -khtml-text-decorations-in-effect: underline; ">http://web.mac.com/martin_jacobs1 </SPAN></A></DIV><BR class="Apple-interchange-newline"></SPAN></SPAN></SPAN> </DIV><BR></BODY></HTML>