* Usage: java -Dpj.np=K [-Dpj.schedule=schedule]
* edu.rit.clu.fractal.MSHistogramClu width height xcenter
* ycenter resolution maxiter outfile
*
K = Number of parallel processes
*
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
*
outfile = Output file name
*
* The program calculates an iteration count i for each pixel in the same * way as the {@linkplain MandelbrotSetSeq} program, with 0 <= i <= * maxiter. The program prints into the output file a histogram of the * i values; that is, for each value of i, how many times that * value occurred in the image. *
* The computation is performed in parallel in multiple processors. The program
* measures the computation's running time, including the time to print the
* output.
*
* @author Alan Kaminsky
* @version 26-Dec-2009
*/
public class MSHistogramClu
{
// Prevent construction.
private MSHistogramClu()
{
}
// Program shared variables.
// Communicator.
static Comm world;
static int size;
static int rank;
// Command line arguments.
static int width;
static int height;
static double xcenter;
static double ycenter;
static double resolution;
static int maxiter;
static File outfile;
// Initial pixel offsets from center.
static int xoffset;
static int yoffset;
// Histogram (array of counters indexed by pixel value).
static int[] histogram;
// Message tag.
static final int HISTOGRAM_DATA_MSG = Integer.MAX_VALUE;
// Number of chunks the worker computed.
static int chunkCount;
// Main program.
/**
* Mandelbrot Set main program.
*/
public static void main
(String[] args)
throws Exception
{
// Start timing.
long t1 = System.currentTimeMillis();
// Initialize middleware.
Comm.init (args);
world = Comm.world();
size = world.size();
rank = world.rank();
// Validate command line arguments.
if (args.length != 7) usage();
width = Integer.parseInt (args[0]);
height = Integer.parseInt (args[1]);
xcenter = Double.parseDouble (args[2]);
ycenter = Double.parseDouble (args[3]);
resolution = Double.parseDouble (args[4]);
maxiter = Integer.parseInt (args[5]);
outfile = new File (args[6]);
// Initial pixel offsets from center.
xoffset = -(width - 1) / 2;
yoffset = (height - 1) / 2;
// Create histogram.
histogram = new int [maxiter + 1];
long t2 = System.currentTimeMillis();
// Compute pixels in parallel.
new WorkerTeam().execute (new WorkerRegion()
{
public void run() throws Exception
{
execute (0, height-1, new WorkerIntegerForLoop()
{
// Compute chunk of pixels, rows lb .. ub.
public void run (int lb, int ub) throws Exception
{
// Count chunks.
++ chunkCount;
// Compute pixels.
for (int r = lb; r <= ub; ++ r)
{
double y = ycenter + (yoffset - r) / resolution;
for (int c = 0; c < width; ++ c)
{
double x = xcenter + (xoffset + c) / resolution;
// Iterate until convergence.
int i = 0;
double aold = 0.0;
double bold = 0.0;
double a = 0.0;
double b = 0.0;
double zmagsqr = 0.0;
while (i < maxiter && zmagsqr <= 4.0)
{
++ i;
a = aold*aold - bold*bold + x;
b = 2.0*aold*bold + y;
zmagsqr = a*a + b*b;
aold = a;
bold = b;
}
// Increment histogram counter for pixel value.
++ histogram[i];
}
}
}
});
}
});
// Reduce histogram into process 0.
world.reduce
(0,
HISTOGRAM_DATA_MSG,
IntegerBuf.buffer (histogram),
IntegerOp.SUM);
long t3 = System.currentTimeMillis();
// Process 0 prints histogram.
if (rank == 0)
{
PrintWriter out =
new PrintWriter
(new BufferedWriter
(new FileWriter (outfile)));
for (int i = 0; i <= maxiter; ++ i)
{
out.print (i);
out.print ('\t');
out.print (histogram[i]);
out.println();
}
out.close();
}
// Stop timing.
long t4 = System.currentTimeMillis();
System.out.println (chunkCount + " chunks " + rank);
System.out.println ((t2-t1) + " msec pre " + rank);
System.out.println ((t3-t2) + " msec calc " + rank);
System.out.println ((t4-t3) + " msec post " + rank);
System.out.println ((t4-t1) + " msec total " + rank);
}
// Hidden operations.
/**
* Print a usage message and exit.
*/
private static void usage()
{
System.err.println ("Usage: java -Dpj.np=