Calculators on the Web

30 March, 2002

Calculators on the Web

Article published in Scientific Computing World, issue 57

What does it all add up to?

Need to make some tricky conversions between units? Never fear, there may be a website out there that can do it all for you, says Michael Kenward

Younger researchers may have heard older colleagues talking fondly of a scientific instrument called a slide rule. It is unlikely, though, that they a will see a slide rule in use. Computers, and their predecessors the scientific calculator, effectively killed off the slide rule.

I sometimes stumble across my own slide rules, but I was reminded of these historical devices when I found a web site with a virtual slide rule. 'Visit the WWW's very first Java Slide Rule.' Well, that's how the site bills this bit of programming. If you cannot lay your hands on a slide rule, try the one here, and admire the generations of scientists who relied on this device for most of their calculation.

The slide rule site, and the online version, is the work of Andrew Davie, who also maintains a web site dedicated to this once influential calculating aid. It turns out that there are people who collect these things.

I came across this site because I wanted to know how far it is from Vancouver to Suffolk. A lead from a fellow writer pointed me at a 'portal' for calculators - more later. I ended up at 'How far is it?'.

This appears to be a travel site, but it still gave me an answer. Not quite the one I needed, there are too few cities outside the USA in the system. But I can tell you that the editorial office of Scientific Computing World is 4694 miles, or 7554 km, or 4079 nautical miles, from Vancouver, which was good enough for my purposes.

The site can show you where these places are on the map, thanks to a link to the Xerox PARC Map Viewer.

After I had dealt with that query, I went in search of calculators of more obvious scientific interest. Well, why bother to write your own software, or even dig out the appropriate software, if you can bookmark a web site?

As in the case of the slide rule, a number of people have deployed their programming skills to write Java calculators. It is nice to see Java doing something useful, rather than providing the bells and whistles and intrusive stuff that crop up at many sites.

One site, the Online Scientific Engineering Calculator, explains why anyone would want to write such a program. One reason is that Java works across operating systems and will work on Macs, PCs and Unix machines.

You can try the pop-up calculator or download the code. There is also a huge pile of online conversions and constants. Plenty of choices here for all but the most obscure units. They even offer to plug gaps, just fill in the form.

The calculator code comes from Flow Simulation, a British company, based in Sheffield, that develops and markets software for scientists and engineers. This is where you can register your use of the software and find the latest updates.

As well as this general calculator, I found some pretty specialist stuff dealing with some obscure units. Take the nuclear industry. Its raw material is uranium, but a lot of the trade is in uranium oxide, or yellowcake (U3O8). It is some time since I felt the urge to know how much uranium you got from a tonne, or even a short ton, of the stuff. But it is nice to know that should I need to make such a calculation it is out there on the web site of the Uranium Institute.

This simple example suggests that a few other businesses might find it worth their while to create a specialist calculator. It is hard to generate traffic for a web site. A calculator is one of the more useful tools that could generate repeat visits.

Naturally enough, the finance people have spotted this and you can find plenty of calculators out there to convert between currencies and to work out the effects of inflation on your savings. Technically oriented business could learn a trick here.

There are probably more astronomers out there than nuclear engineers these days. So the AstroPhysical Calculator is probably more useful to the scientific world. Once again, JavaScript comes into play.

This calculator is pretty old. Like other Java calculators, the astrophysical device credits Rolf Howarth as a source. Indeed, a web search shows that his work is widely disseminated, and credited. Unfortunately, he has moved on since that work, producing lots of dud links. I managed to track him down at Square Box Systems where he has some other Java scripts and his own version of his calculator.

Naturally enough, there are a couple of places where calculators congregate. One is calculator.com. Mostly they want to sell you hardware. But there are also some online calculators here, including one for international time. Other categories include unit converters and currency and scientific calculators.

Another omnibus web site is Martindale's. Jim Martindale seems to have an interesting history as an inventor, among other things, with more than 23 years on the net. It was this site that pointed me towards the online slide rule.

Calculators are not Martindale's only contribution to web cataloguing. His Health Science Guide offers 61,600 teaching files, 129,800 medical cases, 1,160 courses/textbooks, 1,580 tutorials, 4,100 databases and over 10,700 movies. The web site lists 'over 13,135' calculators online. I'll take his word for it. So there's a pretty good chance of finding the calculator that you want here.