Formula Stack

Formula | 1LD | $14.99

Until now, if you wanted the kind of calculator that’s often available on everything from the site that wants sell you a shed, to the B&B that has various different rooms at different prices, to the wood store that sells different cuts and lengths of timber, or the mobile phone company that has different handsets on different monthly price plans, you’d have to take yourself off to somewhere like Code Canyon and integrate it yourself, or engage one of the Rapidweaver developers that undertakes custom work to build one for you.

Not any more. The Formula stack from One Little Designer, is a sophisticated stack which allows you to construct all manner of calculators, style and arrange them and have them deliver a result that lets your visitor see immediately how much X or Y or Z with options A or B or C selected is going to cost them.

There are six different value types – number, checkbox, select (essentially a drop down list) draggable slider, date picker and sub-formula. Values can be added one at a time, assigned a label and displayed as a list or over two columns; then as you add them, you define the kind of value type you want to use and then give it a unique ID, along with a value or value range. The ID is important because once the calculator has been built, you’ll use this to construct the simple mathematical equations which allow the calculator to do its stuff. Along with the standard functions you’d expect like add, subtract, divide and multiply, Formula also supports more complex expressions like greater than/less than, rounding, remainder, square root, sine, cosine, minimum, maximum and so on.

At first sight, these calculations can look a bit daunting, but by chaining them together carefully (1LD recommends you type them out somewhere else first and then copy them in) you can make complex calculations that can be used in many different ways. If that wasn’t enough, you can have several Formula stacks on the same page and combine them to create visitor-friendly yet sophisticated calculation-based forms.

Formula offers plenty of presentational control so you can style it to fit in with your chosen Rapidweaver theme – there are three built in themes which may suit or you can customise your own, with full control over padding, borders, colours, shadows, font family, size, and so on.

There’s no getting around the fact that you’ll need more than a smidgin of school maths to get the best out of the Formula stack, but it’s no more complicated than created formulas in FileMaker or Excel; and once you’ve got the hang of it, you’ll be knocking up bespoke calculators in no time (and even less, when you start saving oft-used ones as partials).

Formula is one of a new breed of stacks that extends Rapidweaver’s functionality way beyond static pages and into areas that are more rewarding and useful for visitors – and for $15.00 it’s really good value for money.

Rob Beattie

Rob Beattie is a freelance copywriter who designs sites using Rapidweaver. He's been reviewing computer hardware, software and web services since 1981. Yes...that long. And he's also the author of 101 Things to Do in a Shed , Fishing: A Very Peculiar History , and The Bluffer's Guide to Fishing