Algorithms on bradleycarey.com

Fractal Mountains in OpenGL using GLUT

Sat, 24 Nov 2012 00:16:21 -0400

This was a project from my Computer Graphics course at Marshall University. The mountains are randomly generated from a normalized pseudo-random number generator and a fractal function. Every time you resize the windows or launch the program, they are drawn differently.

Run-Length Encoding (RLE) in C#

Fri, 17 Aug 2012 14:47:10 -0400

I recently came across a file format that required usage of Run Length Encoding to handle. This involved writing methods for both decoding and encoding. Here are my results:

To decode, you just use a string and concatenate it with each numeric character that is encountered until you hit a non-numeric character. You use this string to figure out how many times you need to repeat the character:

public static string Decode(string toDecode)
{
    string coefficient = String.Empty;
    StringBuilder sb = new StringBuilder();

    foreach (char current in toDecode)
    {
        if (char.IsDigit(current))
            coefficient += current;
        else
        {
            if (coefficient == String.Empty)
                sb.Append(current);
            else
            {
                int count = int.Parse(coefficient);
                coefficient = String.Empty;
                for (int j = 0; j < count; j++)
                    sb.Append(current);
            }
        }
    }
    return sb.ToString();
}

Similarly, for encoding. I used a stringbuilder and a counter to figure out how many times a character was repeated then appended this to the stringbuilder:

Maze Solving Algorithms – Wall Follower

Wed, 15 Aug 2012 10:44:53 -0400

Maze solving algorithms are a well known area of research. Of these, one of the most well known solving strategies for simply connected mazes is the wall follower algorithm. This post will delve into the coding and implementation of such an algorithm (in C#, of course).

Page Replacement Algorithm Benchmarker – Memsim

Mon, 23 Jan 2012 23:11:15 -0400

This Java program simulates three common page replacement algorithms and displays benchmarks such as number of faults (and more). Also provided in the *.rar file is trace files which were captured in Linux and can be loaded into the program via command line to test either LRU, FIFO, or Random algorithms for comparison.

Download memsim.rar

Finding square roots using Newton’s Method (Proof of Concept)

Fri, 16 Oct 2009 23:15:06 -0400

This program uses the famous method by Isaac Newton to iteratively find the square root of a number. It relies upon an inital guess which is then improved until the answer is accurate within 0.000001.

/**
 * Computes square root of a number (Newton's Method)
 * @author Bradley Carey
 * @version 16-Oct-2009
 */
import java.util.Scanner;
public class NewtonsMethod
{
    public static void main(String[] args)
    {
        Scanner myScanner = new Scanner(System.in);
        boolean done = false;
        double guess=0.0;
        while (true)
        {
            done = false;
            System.out.print("\nEnter the number to take the square root of: ");
            String answer = myScanner.nextLine();
            double x = Double.parseDouble(answer);

            if (x<=0)
            {
                System.out.print("Error: only positive inputs are valid.\n");
                return;
            }
            else
            {
                System.out.print("Enter a guess for the square root: ");
                answer = myScanner.nextLine();
                guess = Double.parseDouble(answer);
            }

            while (!done)
            {
                double newGuess = guess-(guess*guess-x)/(2*guess);
                System.out.print("newGuess = " + newGuess + "\n");

                if (Math.abs(guess-newGuess)<0.00001)
                {
                    System.out.print("To within .000001, The square root of " + x + " is " + newGuess);
                    System.out.print("\nDo another? y/n  ");
                    answer = myScanner.nextLine();
                    done=true;

                    if(answer.equals("n"))
                    {
                        System.out.print("Good Bye!!\n");
                        System.exit(0);
                    }
                }
                else
                {
                    guess = newGuess;
                }
            }
        }
    }
}