IMP1 Ruby Tutorial

by **IMP1** Sat Jun 05, 2010 9:32 pm

First off, download the Ruby Installer. It'll allow you to try out ruby by yourself.

Ruby Tutorial I - Maths

Things to know:
In ruby anything after a hash symbol (#) on the same line will be ignored by Ruby and is generally used for making comments about the code.

Ruby can calculate maths for you! But you can't take it into an exam with you. I know, it sucks.

In ruby, there are two types of numbers: Integers, and Floats.
Integers are whole numbers, while floats have decimal points.

Code:: 3, 123, -368 #Integers 3.0, 0.0002, -6.5 #Floats

And Ruby can manipulate these numbers in ways you have never dreamnt of before! Unless you're a bit of a maths geek, and you have dreams about it.
Input:

Code:: 1 + 1 # Addition 4 / 2 # Division 10001 - 10000 # Subtraction 4 * 3 # Multiplication 4 ** 2 # Powers

These will return, as you can probably imagine:
Output:

Code:: 2 2 1 12 16

Bare in mind that when working with integers, the answer will also be an integer, so if you had these:

Code:: 3 / 2 10/3

the result will actually be

Code:: 1 3

as these are the amount of integers.

Likewise, when inputting floats, the answer will be in float form:
Input:

Code:: 4.0 / 2 3 / 2.0 10.0 / 3.0 4.0 / 2.0

Even if the answer is a whole number, it'll still be a float. The answer will such look like this:
Output:

Code:: 2.0 1.5 3.333333333333333 2.0

Ruby can also do more complex mathamatics, such as square roots, and trigonometry and stuffs.
It also allows you to use Pi and E by way of a Math module (You don't need to know what a module is right now, only that it holds stuff like Pi so you can use it)

Let's take a look at what these inputs:
Input:

Code:: Math::Pi # The constant Pi Math::E # The constant e Math.sqrt(4) # Square Root Math.cos(60) # Trig function Math.exp(2) # exponential (e ** number in the brackets) Math.tan(45) # Trig function Math.atan(1) # Arc Tan (opposite to tan)

These bad boys will result in this:
Output:

Code:: 3.14149265358979 2.71828182845905 2.0 # sqrt (Square Root) returns floats -0.952412980415156 # I thought it was a half, but google gives this answer too 7.38905609893065 1.61977519054386 0.785398163397448

Phew, I hate long decimals.

Homework:
Try out some crazy Maths calculations, using parenthesis (silly name for round brackets)
Try these: