Many of the programs I’ve covered in the past have have been

desktop-environment-agnostic—all they required was some sort of

graphical display running. This article looks at one of the programs

available in the KDE desktop environment, KAlgebra.

You can use your distribution’s

package management system to install it, or you can use Discover,

KDE’s package manager. After it’s installed, you can start it

from the command line or the launch menu.

When you first start KAlgebra, you get a blank slate to start doing

calculations.

*Figure 1. When you start KAlgebra, you get a blank canvas for doing
calculations.*

The screen layout is a large main pane

where all of the calculations and their results are displayed. At the

top of this pane are four tabs: Calculator, 2D

Graph, 3D Graph and Dictionary.

There’s also a

smaller pane on the right-hand side used for different purposes

for each tab.

In the calculator tab, the side pane gives a list of

variables, including predefined variables for things like pi

or euler, available when you start your new session. You can add new

variables with the following syntax:

```
a := 3
```

This creates a new variable named `a`

with an initial value of

3. This new variable also will be visible in the list on the right-hand

side. Using these variables is as easy as executing them. For example,

you can double it with the following:

```
a * 2
```

There is a special variable called `ans`

that you can use to get the

result from your most recent calculation. All of the standard mathematical

operators are available for doing calculations.

Figure 2. KAlgebra lets you create your own variables and functions for

even more complex calculations.

There’s also a complete set of functions for doing more

complex calculations, such as trigonometric

functions, mathematical functions like absolute value or floor, and even

calculus functions like finding the derivative. For instance, the following

lets you find the sine of 45 degrees:

```
sin(45)
```

You also can define your own functions using the

lambda operator `->`

. If you want to create a function that

calculates cubes, you could do this:

```
x -> x^3
```

This is pretty hard to use, so you may want to assign it to a variable

name:

```
cube := x -> x^3
```

You then can use it just like any other function, and it also shows up in

the list of variables on the right-hand side pane.

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