/*
* Copyright (C) 2008 Yohan Liyanage.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package test.mandelbrot;
import org.nebulaframework.core.task.GridTask;
import org.nebulaframework.grid.GridExecutionException;
public class MandelbrotTask implements GridTask<MandelbrotResult> {
private static final long serialVersionUID = 8435497590730632638L;
private static final long MAX_ITERATIONS = 1000000L;
// region for which application is computing Mandelbrot
private double x1; // starting x1,y1
private double y1;
private double x2; // ending x2,y2
private double y2;
// slice of the region this task computes
private int start; // starting scan line
private int width; // width of scan line in image
private int height; // number of scan lines in image
private int lines; // number of scan lines per task
public MandelbrotTask(double x1, double y1, double x2, double y2,
int start, int width, int height, int lines) {
super();
this.x1 = x1;
this.y1 = y1;
this.x2 = x2;
this.y2 = y2;
this.start = start;
this.width = width;
this.height = height;
this.lines = lines;
}
public MandelbrotResult execute() throws GridExecutionException {
try {
// Check for pre-conditions
doAssertions();
// Do Execution
return processMandelbrot();
} catch (Exception e) {
throw new GridExecutionException(e);
}
}
private MandelbrotResult processMandelbrot() {
double x, y, xx, a, b;
int end = start + lines;
double da = x2/width;
double db = y2/height;
b = y1;
long[][] points = new long[width][lines];
for (int i = 0; i < start; i++) {
b = b + db;
}
int k = 0;
for (int i = start; i < end; i++, k++) {
a = x1;
for (int j = 0; j < width; j++) {
long n = 0;
x = 0.0;
y = 0.0;
while ( (n < MAX_ITERATIONS) && ( (x*x)+(y*y) < 4.0) ) {
xx = x * x - y * y + a;
y = 2 * x * y + b;
x = xx;
n++;
}
points[j][k] = n;
a = a + da;
}
b = b + db;
}
return new MandelbrotResult(start,lines, points);
}
private void doAssertions() throws GridExecutionException {
try {
if (start<0) throw new AssertionError("start");
if (width<=0) throw new AssertionError("width");
if (height<=0) throw new AssertionError("height");
if (lines<=0) throw new AssertionError("lines");
}
catch(AssertionError ae) {
throw new GridExecutionException("GridTask Assertions Failed");
}
}
}