I was interested in tye's quip about dealing with unit specifications such as 'kg/m/m' vs 'kg/m^2'...so I started digging around on CPAN for tokenizers that might assist in normalizing unit representations. There's some infix/postfix stuff, as well as various tokenizers such as Math::Expr that might be of assistance here.

Perhaps more importantly, there's some unit conversion modules already out there that might bear further scrutiny:

Math::Units
Convert-Units
Math::Calc::Units

Of these, the Convert-Units bundle seems to be on the money, since in the author's words:

It is intentionally distinct from the Math::Units module. Why? The Math::Units module implies that unit conversions are exact, with one-to-one relationships. This is fine for scientific work. It's even fine for some general purpose/real-world uses (such as converting Fehrenheight to Celcius).

Real-world measurement systems are conflicting. For instance, a "point" in typography is equivalent to 1/72 inch, according to PostScript specs and common usage. Other type systems consider it 1/72.27 inch, or 0.01383 inches, or 0.0148 inches. Outside of that context, a point may be 1/120 or 1/144 inch.

Common notations and abbreviations also depend on context. Does "12 pt" mean "12 point", "12 parts" or "12 pints"?

Even without conflicts in the definition of a particular unit, there's no need to convert point sizes for fonts into miles or light-years. Typesetters, surveyors and astronomers user different scales as well as systems.

Hope these are of assistance. At the very least, you can mine the modules for conversion tables!

Matt

In reply to Re: The Definitive Unit Conversion Script by mojotoad
in thread The Definitive Unit Conversion Script by Aristotle

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