If you'd like to skip the why and just see how to use abakus, please click here.

Abakus is a calculator designed with computer usability in mind, as opposed to just being a clone of your desktop calculator. Instead of using your powerful computer to put a limited simulation of a calculator on-screen, Abakus instead allows you to use your computer to its greater potential.

Enough of the metaphysics, how about an example of what I'm talking about? Let's use KCalc, the normal KDE calculator program as an example, trying to calculate 3 multiplied by the sine of 50 degrees. First you would do something like the following:

1. Make sure you're in Degrees mode:


2. Then, click on the '5' and the '0' buttons:


3. You would then search for the 'sin' button and click it, which would immediately calculate a result:


4. Then, click the 'X' button, and notice that there is no user feedback whatsoever. Even real calculators temporarily blank the display:


5. Then, we click the '3' button and watch as our previous result suddenly disappears. This isn't KCalc's fault: It has nowhere else to display the 3:


6. Proceeding boldly forward with the faith that our previous result wasn't lost, we click the '=' button to perform the multiplication:

Although we did get the result, this is unsatisfactory for several reasons. A computer monitor has plenty of room to display text, there's no reason why you should ever be confused about what step your calculator is about to make, or whether it remembered an intermediate result. Computers are also much more powerful than your $10 desktop calculator, so there's no reason that you should be forced to type your expression in a form suitable for your calculator. Roberto Alsina picked up on this in a rant he published, A Modest Usability Improvement

Now let's try the same thing in Abakus, which is designed to help you with your calculating, instead of bending you to its will. As with KCalc, extraneous portions of the GUI have been hidden.

1. We still need to make sure we're in Degrees mode:


2. Now we can type "3sin 50", just as we'd write it on paper. Sometimes it's better to clarify things, both for reading and to clarify your intentions to abakus. So you can also use the parentheses to group operations like you would on paper, and the '*' operator to explicitly multiply, like this: "3 * sin (50)":


And we're all done! We even typed in the same expression two different ways to demonstrate how abakus will try very hard to guess what you're trying to calculate. You'll notice that KCalc and abakus both agree on the answer.

If you're still reading you've probably been sold by Roberto's argument, just as I was when I started writing abakus. So read on, if you want to find out all that abakus can do for you.

The basic synposis is: Type and your expression, and hit Enter. Abakus will calculate the value of what you typed and display it on the screen. You can use many functions from mathematics, and even define your own functions. You can also define and use variables.

You can define your own functions in abakus. To do so, at the expression prompt, you would type something like: set funcname(var) = expr and hit Enter. If all went well Abakus will simply output "OK", and you'll see your function appear in the user-defined function list. Now you can use your function as normal. If you'd like to remove your function, you can either right-click on it in the user function list and select "Remove Function", or enter remove funcname() in the expression prompt and hit Enter. Note that you don't enter the variable name in the parentheses since only the function name is needed. (The reason you still need the parentheses is because your variables can have the same name as a function).

You can also define your own variables. Abakus comes with the basic mathematical constants pi (π) and e (Euler's Constant) defined by default. To define your own variable, at the expression prompt you would type: name = value, or set name = value. You will then see your variable in the list of variables. To remove your variable, either right-click on it in the list and select "Remove Variable", or enter remove varname in the expression prompt. Notice that there are no parentheses this time. ;-)

You may have noticed that when you type in expressions, Abakus will show a value beginning with $ (such as $0) after the result. This is a placeholder variable. What happens is that the most recent result is always $0. The result directly before is $1, and so on. You may use the placeholder values in your expression to avoid having to re-type it or use the drag-and-drop. Note that there is a special variable defined called ans, which is the same as $0. In other words, whenever you want to reference the last expression's result, you can use $0 or ans.

Abakus supports high-precision arithmetic using Ariya Hiyadat's hmath code from his excellent calculator SpeedCrunch. You can change the displayed precision by using the View Menu, where you can select between Automatic precision, or some pre-defined precision levels. You can also select Custom precision to select your own precision (between 0-75 digits).

Abakus supports all the standard operators like -, +, *, and /. It also supports both the ^ and ** symbols to mean exponentiation. Exponentiation is right-associative in Abakus, meaning that 2^3^2 will return 512 instead of 64. (2^(3^2)). Operator precedence is performed as in mathematics as well (e.g. 2 + 3 * 2 and 3 * 2 + 2 both return the same answer). Abakus also supports parentheses to group expressions for when the default operator precedence is invalid.

Abakus has quite a few functions built-in:

There are many cool things yet to add to Abakus. Here's a partial list of things that Abakus doesn't support:

Please contact michael.pyne@kdemail.net for bug reports and feature requests.