edu.rit.hyb.fractal
Class MandelbrotSetHyb

java.lang.Object
  extended by edu.rit.hyb.fractal.MandelbrotSetHyb

public class MandelbrotSetHyb
extends Object

Class MandelbrotSetHyb is a hybrid parallel program that calculates the Mandelbrot Set. The program runs with one process per node and multiple threads per process. The program uses the master-worker pattern for load balancing. Each thread in the program is an independent worker thread. Each worker thread calculates a series of row slices of the Mandelbrot Set image, as assigned by the master thread. Each worker writes its own slices to its own (partial) PJG image file. The per-worker image files can be combined offline into a single image file if desired.

The row slices are determined by the pj.schedule property specified on the command line; the default is to divide the rows evenly among the workers (i.e. no load balancing). For further information about the pj.schedule property, see class PJProperties.

Usage: java -Dpj.np=Kp -Dpj.nt=Kt [ -Dpj.schedule=schedule ] edu.rit.hyb.fractal.MandelbrotSetHyb width height xcenter ycenter resolution maxiter gamma filename
Kp = Number of parallel processes
Kt = Number of parallel threads per process
schedule = Load balancing schedule
width = Image width (pixels)
height = Image height (pixels)
xcenter = X coordinate of center point
ycenter = Y coordinate of center point
resolution = Pixels per unit
maxiter = Maximum number of iterations
gamma = Used to calculate pixel hues
filename = PJG image file name

If filename is specified as, for example, "image.pjg", then the per-worker image files are named "image_0.pjg", "image_1.pjg", and so on through Kp*Kt-1.

The program considers a rectangular region of the complex plane centered at (xcenter,ycenter) of width pixels by height pixels, where the distance between adjacent pixels is 1/resolution. The program takes each pixel's location as a complex number c and performs the following iteration:

z0 = 0
zi+1 = zi2 + c

until zi's magnitude becomes greater than or equal to 2, or i reaches a limit of maxiter. The complex numbers c where i reaches a limit of maxiter are considered to be in the Mandelbrot Set. (Actually, a number is in the Mandelbrot Set only if the iteration would continue forever without zi becoming infinite; the foregoing is just an approximation.) The program creates an image with the pixels corresponding to the complex numbers c and the pixels' colors corresponding to the value of i achieved by the iteration. Following the traditional practice, points in the Mandelbrot set are black, and the other points are brightly colored in a range of colors depending on i. The exact hue of each pixel is (i/maxiter)gamma. The image is stored in a Parallel Java Graphics (PJG) file specified on the command line.

The computation is performed in parallel in multiple processors. The program measures the computation's running time, including the time to write the image file.


Method Summary
static void main(String[] args)
          Mandelbrot Set main program.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

main

public static void main(String[] args)
                 throws Exception
Mandelbrot Set main program.

Throws:
Exception


Copyright © 2005-2012 by Alan Kaminsky. All rights reserved. Send comments to ark­@­cs.rit.edu.