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What is a snail?

Everything in a cell technically happens "in water", but the hydrophobic inner layers of proteins do not have as much water as the outside, making the ionic interactions in the inside rather strong, and the ionic interactions outside in the cytosol rather weak (20kJ/mol).

This is a simple program written using R, which is one of the most popular programming languages in the world for scientific or non-scientific research, and which has tons of open-source, free resources. This entire ebook is written and hosted online entirely for free using an R library called Bookdown.

You do not need to know R for any introductory classes at queens college. Instead, CS111 and CS211 use C++, the language R was made with, which is somewhat similar. A fun exercise for yourself in the semester would be to write this program using C++ (a function called rand() would help you with that).

The program itself simply simulates flipping a coin. If the coin is heads, the program spits out "do it". If it's tails, it spits out "Do it anyway". You can see the result at the bottom next to the [1].

To see what each line does, walk through each annotation of the lines.

This line takes in a list of two words ("heads" and "tails") and stores it in a variable called coin. In programming, "words" like this are often called strings.

The arrow is called an "assignment operator", which is just a fancy way of saying it takes the thing on the right and "assigns" the name on the left to it, which results in the thing on the right getting stored with that name in your computer's memory. Usually the equals sign = is used for this in programming languages, but in R it's an arrow <-.

This line uses a function in R called sample(), which takes the list coin, and chooses one of the words in it randomly (the 1 means "choose only one word").

Functions are anything which takes something in, does something to it or something else, and spits something out (your oven is a function). The arrow is taking what is spit out by the function (the result of the coin flip), and putting it in a variable called flip.

To put something in a function, put it in the parentheses (usually you have to stick the thing in a variable, like we did with the list we put in coin). Many functions take in more than one thing (these are multivariable functions).

This ebook was hosted on the internet using exactly one line of code which includes exactly one function, this one:

publish_book()

So you can do a lot with computers without knowing much programming!

This line, and everything after it, form something called a "conditional". All conditionals look something like this, even in other languages like C++ or Python:

if (some sentence) {
    Do this
} else {
   Do some other thing
}

The sentence in the parentheses right after the "if" is called "the condition". All this thing does is check if the condition ("some sentence", or in this case, the result of the coin flip being the word "heads") is true. If the condition is true, the thing in the curly brackets happens.

If the condition is not true, the thing in the second pair of curly brackets happens (that's why there's an "else" there). Essentially a conditional is saying "if this happens, do this, but if anything else happens, do this instead".

There was a whole section before this that I missed! Anyone get it?

Why do we skip to 26 here?

This line takes in a number from the user (storing it in something called cin and then puts it in the change variable.

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$$y = \textrm{some number} \times 5^{2}$$

The animation above here is cyclohexane, an organic compound, moving through its possible orientations. It was made using Chem Doodle's open-source web components library.

In case you just clicked here wondering why the text is highlighted, this comment pane is hypothes.is, an open-source tool meant to get people to interact on webpages. If you hit "sign up", you can make an account, and hypothesis will save any comments you make about text on a web page, and it will save things you highlighted so you can study them later.

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I don't know what this meeeeaana

In how much detail should we know the differences between Viruses, Viroids, Virusoids, and so on?

Do you think we should ask Prof. Dennehy how relevant the chemistry of lipids hiding from water is? That is, should we know a lot about entropy?

This is a test!

This is an annotation. You can highlight text and comment on it to suggest a change or addition to the book, or you can just ask a question about it for further clarification. For large additions to the book, make a change to the code on GitHub using the edit button in the toolbar in the top right corner next to the capital A.

I wrote this! And the site works! Eureka!

I wrote this!