New Design Launched – I got up at 4am to put the finishing touches to a complete redesign of the site. By the time I had to leave for my day job, it was up and running. I think the design improves significantly on the previous version, but you can judge for yourself at www.calcatraz.com (oh, and let me know what you think using the feedback form…).

User Accounts Launched - On my lunch break I forewent the traditional pub lunch, and took my laptop down to a cafe where I nutted out the last of the code for handling user accounts. Then immediately after work I headed back to the cafe and pushed the code live. So you can now sign up for a free Calcatraz Account which gives you permanent access to your full calculation history and touch-typing history (on the Calculator and Typist apps respectively).

Melbourne Lean Startup Meeting - Calcatraz then took its first steps into the wider world at last night’s lean startup meeting. The night featured awesome talks from the NineFold, RomeToRio and Kaggle guys. It was also great to talk to people doing some really interesting stuff in the startup space, including Peter, Daryl, Jai from UnBaa (a social decision making site), and Anita from TechSeeder. Cheers guys!

So yeah, quite a day overall! P.S. Here’s the new design:

A while ago I decided to try and up my typing speed. I tried out as many online tools as I could find, but found they all fell into one of two categories: fancy full-featured desktop programs with free trials and an otherwise hefty price tag; or online apps which do nothing but measure your typing speed.

The speed testers were fine for benchmarking, but of no use in actually improving typing speed. Which left the costly desktop apps. Aside from the obvious problems of price and poor portability, I came across some deeper problems as I persevered with them.

Most significantly, I discovered they were actually quite sub-optimal. They centered around lessons focusing on particular groups of letters – the implicit and incorrect assumption being that these are the letters which, if trained, would most improve your typing speed.

Some would go a step further and offer follow up training in the letters from that group on which you performed slowest. Even ignoring the almost certainly sub-optimal letter group selection, training the slowest letters is sub-optimal in its own right. If the slow letters are uncommon ones – which, let’s face it, will tend to be the slowest due to their placement on the keyboard – then their contribution to the total time taken to type English text will be minimal. And therefore so will any improvement.

Rather than waste my time with inefficient tools, I decided I would be better off writing my own typing trainer. Thus Calcatraz Typist was born.

Calcatraz Typist approaches the problem differently to other apps. It is web-based and free. It has a single, simple typing test mode. It presents you with a list of words, which you must type in correctly. As you do it tracks your key press speeds. It then computes the next list of words based on this. The list of words is computed such that training on it, out of all possible lists, will yield the greatest increase in the speed with which you can type standard English text. No other typing tutor I tested offered training optimized for this goal. Yet this is undoubtedly the goal of most people working to improve their typing skills.

There is little more to the app than this. You type in the words, gain the optimal improvement, then repeat. Through precise measurement and calculation of your key speeds at each step it constantly adapts to your changing abilities.

As you go it displays a graph which shows both the speed with which you complete the tests, and your “real” speed, which is the calculated speed at which you will be able to write standard English text.

It also works equally well for keyboard layouts other than qwerty – for instance Dvorak, which I am learning.

If you are looking for typing training which is both efficient and free, I invite you to try out Calcatraz Typist.

Anyone watching the site will have noticed that things have been a bit quiet for the last few months. Calcatraz has definitely not been forgotten, however. I’ve been busily working away on a complete redesign of the calculator, which I hope to begin rolling out soon.

I’ve also been working on a number of other apps which will soon start to join Calcatraz online.

For the moment, though, I’d just like to share something quick that I knocked up a while ago – a slimmed down version of the calculator designed for use on mobile phones and other small screen internet enabled devices. It can be accessed at:

http://www.calcatraz.com/mob

I hope to follow it with an iPhone app somewhere down the line too.

• Removed some external file includes which were no longer needed
• Implemented better caching to prevent unnecessary re-requests
• Modified the core to minimise the amount of work being performed in the most-frequently used code.

The last of these required some profiling to be performed. For this I used webgrind for PHP (which requires xdebug to be installed, which I did on my local testing environment). While this set-up was a bit fiddly to get going, it was worth it as it let me pinpoint exactly where performance was being the most affected. As a result I was able to cut calculation time down from 2.5 to around 0.5 seconds on average. The result is faster page loads every time.

One of the main improvements made was to significantly improve the user interface. I noticed that users appeared to be getting confused by the sudden jump from the neat front page to a much more cluttered calculation result page. To resolve this I consolidated the two into a single page which acts as both the front page and the calculation result page, removing much of the clutter in the process. The result was an immediate increase in the number of users successfully performing calculations.

In addition, I also extended the range of core calculations performed from some basic calculations to a range of scientific calculations. To this added the ability to perform many unit conversions and, more recently, currency conversions. Another new feature with which I’m particularly happy is the display of full calculation workings.

2010

Moving on, I have many improvements planned for 2010.

I have already taken a number of steps behind the scenes to increase the amount of time I have free to spend on Calcatraz development, which should see an increase in the rate of improvement.

The focus for the start of the year is going to be on the continued improvement of calculation results. As well as improving on current answers, I’m looking to continue to expand the depth and range of calculations performed. This will involve further additions to the core, unit conversion and currency conversion modules. Additionally, several new modules will be added extending the types of calculations Calcatraz can perform.

A number of enhancements to the core algorithms are planned. These enhancements will increase automation within the development process, freeing up time for development in other areas. They are also expected to enhance the quality of calculation results.

I’m also looking to improve documentation and provide a much easier and more comprehensive set of help guides. While Calcatraz is intended to answer any calculation posed to it, it will be useful at this early stage in its development to assist users in finding the right way to express their calculation. It should also serve as a useful range of examples to illustrate what can be done.

Of particular importance is the value provided to users. I will be actively attempting to measure the levels of value provided and make use of opportunities to increase that value. Hopefully, in doing so I can tailor the calculator more accurately to the needs of the user.

I expect 2010 to bring about a significant maturing of Calcatraz as an online calculator. Perhaps I will plan a ‘launch’ towards the end of the year. Alternatively I may just continue on the path of continual improvement and allow the quality of the calculator to speak for itself.

I hope you have a happy new year, and continue to enjoy my ever improving calculator.

General Calculators

This section lists calculators which offer general calculation capabilities. These allow you to simply type any calculation into a free-form text box which they then try to answer.

Calcatraz – My free online calculator offering scientific, unit and currency calculations. Shows workings and a history of previous calculations.

CalculateForFree multiple functions – A calculator script with many functions. This calculator includes different measures conversion, rule of three, temperature conversion and other formulas.

Google calculator – Google will provide answers to calculations entered into the main search box.

Instacalc - The fast, easy shareable online calculator.

Wolfram|alpha – A computational knowledge engine. Enter a query and it uses its built-in algorithms and a growing collection of data to compute the answer.

Task-Specific Calculators

This section is for calculators which provide one specific function (e.g. scientific calculator, tax calculator, etc).

CalculateForFree -Free calculators for home, work and school. The main page offers a basic calculator with links to a wide range of specific calculators including travel, poker odds and global warming calculators.

Calculator.com – Another site with a number of specific calculators, including mortgage, math, loan, finance, scientific, health & sports calculators.

CalculatorSoup - As with the previous two, Calculator Soup offers a range of calculators for specific calculations, such as algebraic and geometric calculations.

Calculator.net – Claiming to be the richest collection of free online calculators, it offers a large number of specific calculators including mortgage and loan calculators and a number sequence calculator.

Math.com – A collection of specific calculators including trigonometry, probability and finance calculators.

List of Online Calculator Lists

Looking for something not on this list? Here are some other great lists of web-based calculators (I’ll be adding to this as I come across new lists):

Numa - A list of calculators for traders looking to price options, etc.

List of Online Graphing and Scientific Calculators - The title says it all really – if you’re after a graphical calculator, this could be a good place to start.

Top 10 Online Calculator Directories – This is getting a bit meta now – as this is itself a list of online calculator lists, it should really be in its own list. Oh well!

Well that’s it for now! If you know of a web-based calculator which isn’t on this list, but should be, please let me know in the comments.

The fast, easy and shareable online calculator.

I’ll be doing some further refinements on the user interface in the near future to further improve it and in particular clean up the history tab which I’m still not entirely happy with. But I wanted to get the new interface up now to see how well it is received and to identify any sticking points.

You can check out the new interface in action on the main site: www.calcatraz.com.

• A new user interface – the old Calcatraz interface has two main pages: the home page with a single calculation entry box, and the main calculation page which shows a history of calculations and other information. One thing I found was that the transition from the home page to the more cluttered calculation page was confusing to users. As a result I’ve been developing a new user interface which has a single screen (which is sort of half-way between the two old pages). This hides less commonly used features and removes the ‘surprise’ element which used to arise when a user was sent to the second page. Hopefully this will make the calculator more user-friendly and consistent to use. It also has the added benefit of reducing the amount of code and effort from that required to maintain two separate pages.
• A static blog. As a small startup, time is a precious commodity. I can’t really justify the time cost of maintaining an up-to-date wordpress installation. To solve the problem once and for all I”m creating some code which copies each html page produced by the blog. The result is a static html version of the blog. It has a number of benefits. First is that security problems are virtually eliminated as the only thing that will be placed on the webserver is static html. The second is that, as static html, pages will load more quickly than interpreted code. This will provide users with a better user experience. The main downside is that I will have to disable comments. However, this is a trade-off I’m willing to make as this site is mainly informational. I may look at reintroducing comments in some other form at a later time.
• General optimisations. One of my main aims for the calculator is that it should be fast. To this end I’ve been implementing a number of optimisations. For example I’ve modified my build process to minify javascript and css (that is, remove unnecessary comments and characters, to reduce size and therefore load time). This will be applied to the live site as soon as I finish my changes to the user interface and perform a site update.
• Core algorithm updates. I’ve been making a number of changes to the core algorithms to provide results more quickly. I hope to be able to share these details at some point in the future.

So while there hasn’t been much in the way of observable changes to the site, there has been a lot going on in the background. When I finish up these loose ends then I’ll update the live site. I hope you like the improvements.

This “book” is the user manual for Calcatraz, the online calculator. It will be the most comprehensive and accurate source of information on Calcatraz. As well as covering basic usage it will cover advanced features and tips and tricks.

Using the Calculator

• Overview of the homepage
• Overview of the main calculation page
• Basic operators
• Scientific calculations
• Unit conversions
  • Distance conversions
  • Weight conversions
• Currency conversions
• View the calculation workings

Advanced Features

• Rules