Normal Distribution in Sugarcube 2

IGotsAQuestion · October 2016

Hello everyone. First post here.

I tried searching for how to do normal distribution in Sugarcube 2 but nothing comes up, but I could find how to do it in javascript (which I know next to nothing about). I did find this javascript function that fits the bill for what I want and I want to know how I can implement it in the 'Edit Story Javascript' menu for use with Sugarcube 2:

// returns a gaussian random function with the given mean and stdev.
function gaussian(mean, stdev) {
var y2;
var use_last = false;
return function() {
var y1;
if(use_last) {
y1 = y2;
use_last = false;
}
else {
var x1, x2, w;
do {
x1 = 2.0 * Math.random() - 1.0;
x2 = 2.0 * Math.random() - 1.0;
w = x1 * x1 + x2 * x2;
} while( w >= 1.0);
w = Math.sqrt((-2.0 * Math.log(w))/w);
y1 = x1 * w;
y2 = x2 * w;
use_last = true;
}

var retval = mean + stdev * y1;
if(retval > 0)
return retval;
return -retval;
}
}

I found this at http://stackoverflow.com/questions/25582882/javascript-math-random-normal-distribution-gaussian-bell-curve.

At first I tried other methods that worked, but they didn't have mean and standard deviation variables which I need, but I have no idea how to convert this from javascript. So how can I get this to work in Sugarcube 2 so I can just write <<set $variable to gaussian(80, 10)>> for example?

Thanks in advance.

TheMadExile · October 2016

First. Please use the code tag when you're posting code—it's C on the editor bar.

That bit of code is what's known as a factory—i.e. it returns an object or function for you to use, it doesn't return data directly. In this case, it's a factory for Gaussian functions.

Open your project's Story JavaScript, paste that code into it, and then do something like the following after it:

setup.standard = gaussian(80, 10);

That creates a Gaussian function, which when called will give the results you're looking for, and assigns it to the special setup object with the name standard.

To use it within your code:

<<set $variable to setup.standard()>>

You may name the created function, or functions if you need more than one distribution, pretty much whatever you want.

IGotsAQuestion · October 2016

Thank you very much, that worked perfectly.

Edit: Realised that though it now works, I couldn't actually change the value of the mean and standard deviation of the gaussian function within a passage.

How do I make it so that I can for example type:

<<set $variable to gaussian(50, 5)>>

TheMadExile · October 2016

You don't. The generated Gaussian function depends on state created for it by the factory. Allowing different values to be passed would skew the results.

As I noted before, however, you may generate as many Gaussian functions as you need, just give them unique names. For example:

setup.standard80_10 = gaussian(80, 10);
setup.standard50_5 = gaussian(50, 5);

And to use them within your code:

<<set $aVariable to setup.standard80_10()>>
<<set $bVariable to setup.standard50_5()>>

Those names are pretty bad, however, you should get the idea.

IGotsAQuestion · October 2016

That makes sense, thanks for the help.

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Normal Distribution in Sugarcube 2

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