A generic Fisher-Yates Shuffle

It’s been a long time I have done any activity in this blog. I was going through some old stuffs and thought to post something. Today I will post a generic implementation for Fisher-Yates Shuffle.

Although you can get the Fisher-Yates algorithm from wiki, still I am briefly explaining it.

Let us assume that there is a array arr of length n. We need to find a uniformly random permutation of the elements of the array. One of the variations of the algorithm is as follows.

arr is an array of length n, where indexing starts from 0
i=n-1
while i>0
{
  r = generate a random number between 0 and i (both inclusive)
  swap the array elements arr[r] and arr[i]
  i = i - 1
}
arr is now uniformly permuted

Continue reading “A generic Fisher-Yates Shuffle”

Plot histogram in terminal

We had assignments to print “*”s in different formation in undergraduate class, which I never liked as they were pointless. Now I got a somewhat justifiable application, plot histogram in terminal. In the last post Generating random numbers from Normal distribution in C I posted the C code to generate random numbers from the Normal distribution using the Polar method. In this post I am posting a simple code to plot the histogram of generated random numbers from this or any other distribution. Let me first post the code and then explain what is going on. Continue reading “Plot histogram in terminal”

Generating random numbers from Normal distribution in C

I needed to write a random number generator in C which will generate random numbers from Normal Distribution (Gaussian Distribution). Without this component I couldn’t proceed to finish writing a C code for Heuristic Kalman Algorithm by Lyonnet and Toscano for some experiments. I selected the Marsaglia and Bray method also known as the Polar method to generate Normal random variables. Here is how it is done. Continue reading “Generating random numbers from Normal distribution in C”