File: HotSpotSeq.java

package info (click to toggle)
libpj-java 0.0~20150107%2Bdfsg-4
  • links: PTS, VCS
  • area: main
  • in suites: bookworm, bullseye
  • size: 13,396 kB
  • sloc: java: 99,543; ansic: 987; sh: 153; xml: 26; makefile: 10; sed: 4
file content (335 lines) | stat: -rw-r--r-- 11,007 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
//******************************************************************************
//
// File:    HotSpotSeq.java
// Package: edu.rit.clu.heat
// Unit:    Class edu.rit.clu.heat.HotSpotSeq
//
// This Java source file is copyright (C) 2008 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.clu.heat;

import edu.rit.color.HSB;

import edu.rit.image.ColorImageRow;
import edu.rit.image.PJGHueImage;
import edu.rit.image.PJGImage;

import edu.rit.pj.Comm;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;

/**
 * Class HotSpotSeq is a sequential program that calculates the temperature
 * distribution over a metal plate with hot spots.
 * <P>
 * Usage: java edu.rit.clu.heat.HotSpotSeq <I>imagefile</I> <I>H</I> <I>W</I>
 * <I>rl1</I> <I>cl1</I> <I>ru1</I> <I>cu1</I> <I>temp1</I>
 * [ <I>rl2</I> <I>cl2</I> <I>ru2</I> <I>cu2</I> <I>temp2</I> . . . ]
 * <BR><I>imagefile</I> = Output image file name
 * <BR><I>H</I> = Mesh height in pixels (<I>H</I> &gt;= 1)
 * <BR><I>W</I> = Mesh width in pixels (<I>W</I> &gt;= 1)
 * <BR><I>rl1</I> = First hot spot lower row (1 &lt;= <I>rl1</I> &lt;=
 * <I>W</I>)
 * <BR><I>cl1</I> = First hot spot lower column (1 &lt;= <I>cl1</I> &lt;=
 * <I>W</I>)
 * <BR><I>ru1</I> = First hot spot upper row (1 &lt;= <I>ru1</I> &lt;=
 * <I>W</I>)
 * <BR><I>cu1</I> = First hot spot upper column (1 &lt;= <I>cu1</I> &lt;=
 * <I>W</I>)
 * <BR><I>temp1</I> = First hot spot temperature (0.0 &lt;= <I>temp1</I> &lt;=
 * 100.0)
 * <P>
 * The program sets up a mesh of equally-spaced points with <I>H</I>+2 rows and
 * <I>W</I>+2 columns. The temperature of each boundary point [<I>r,c</I>],
 * where <I>r</I> = 0, <I>r</I> = <I>H</I>+1, <I>c</I> = 0, or <I>c</I> =
 * <I>W</I>+1, is fixed at 0.0. The temperatures at certain interior points,
 * known as "hot spots," are fixed at certain values greater than 0.0.
 * Specifically, the temperature of each point in the rectangle from
 * [<I>rl1,cl1</I>] to [<I>ru1,cu1</I>] inclusive is fixed at <I>temp1</I>, the
 * temperature of each point in the rectangle from [<I>rl2,cl2</I>] to
 * [<I>ru2,cu2</I>] inclusive is fixed at <I>temp2</I>, and so on. The program
 * calculates the temperature at every interior point (other than the hot spots)
 * using successive overrelaxation with Chebyshev acceleration and red-black
 * updating. The program outputs a PJG color image <I>H</I>+2 pixels high and
 * <I>W</I>+2 pixels wide. Each pixel's hue depends on the corresponding mesh
 * point's temperature. A temperature of 0.0 is blue; a temperature of 100.0 is
 * red; intermediate temperatures are intermediate hues. The PJG image file is
 * named <I>imagefile</I>.
 * <P>
 * The computation is performed sequentially in a single processor. The program
 * measures the computation's running time. This establishes a benchmark for
 * measuring the computation's running time on a parallel processor.
 *
 * @author  Alan Kaminsky
 * @version 11-Apr-2008
 */
public class HotSpotSeq
	{

// Prevent construction.

	private HotSpotSeq()
		{
		}

// Hidden constants.

	private static final double MIN_TEMP = 0.0;
	private static final double MAX_TEMP = 100.0;
	private static final double DELTA_TEMP = MAX_TEMP - MIN_TEMP;

	private static final double MIN_HUE = 4.0/6.0;
	private static final double MAX_HUE = 0.0;
	private static final double DELTA_HUE = MAX_HUE - MIN_HUE;

	private static final double EPS = 1.0e-3;

// Hidden variables.

	// Command line arguments.
	static File imagefile;
	static int H;
	static int W;

	// Temperature mesh.
	static double[][] h;

	// Mesh of hot spot locations.
	static boolean[][] hotspot;

	// Variables for total absolute residual.
	static double EPS_initialTotalAbsXi;
	static double totalAbsXi;

	// Other variables used in the successive overrrelaxation algorithm.
	static int MAXITER;
	static double rho_s_sqr;
	static double omega_over_4;
	static int iterations;

// Main program.

	/**
	 * Main program.
	 */
	public static void main
		(String[] args)
		throws Exception
		{
		Comm.init (args);

		// Start timing.
		long t1 = System.currentTimeMillis();

		// Parse command line arguments.
		if (args.length < 8 || (args.length % 5) != 3) usage();
		imagefile = new File (args[0]);
		H = Integer.parseInt (args[1]);
		W = Integer.parseInt (args[2]);
		if (H < 1) usage();
		if (W < 1) usage();

		// Initialize temperature and hot spot meshes.
		h = new double [H+2] [W+2];
		hotspot = new boolean [H+2] [W+2];

		// Record hot spot coordinates and temperatures.
		int n = (args.length - 3) / 5;
		for (int i = 0; i < n; ++ i)
			{
			int rl = Integer.parseInt (args[3+5*i]);
			int cl = Integer.parseInt (args[4+5*i]);
			int ru = Integer.parseInt (args[5+5*i]);
			int cu = Integer.parseInt (args[6+5*i]);
			double temp = Double.parseDouble (args[7+5*i]);
			if (1 > rl || rl > W) usage();
			if (1 > cl || cl > H) usage();
			if (1 > ru || ru > W) usage();
			if (1 > cu || cu > H) usage();
			if (MIN_TEMP > temp || temp > MAX_TEMP) usage();
			for (int r = rl; r <= ru; ++ r)
				{
				double[] h_r = h[r];
				boolean[] hotspot_r = hotspot[r];
				for (int c = cl; c <= cu; ++ c)
					{
					h_r[c] = temp;
					hotspot_r[c] = true;
					}
				}
			}

		// Compute initial total absolute residual, then multiply by EPS.
		totalAbsXi = 0.0;
		double xi;
		for (int r = 1; r <= H; ++ r)
			{
			double[] h_rm1 = h[r-1];
			double[] h_r   = h[r];
			double[] h_rp1 = h[r+1];
			boolean[] hotspot_r = hotspot[r];
			for (int c = 1; c <= W; ++ c)
				{
				xi =
					hotspot_r[c] ?
						0.0 :
						h_rm1[c]+h_rp1[c]+h_r[c-1]+h_r[c+1]-4.0*h_r[c];
				totalAbsXi += Math.abs (xi);
				}
			}
		EPS_initialTotalAbsXi = EPS * totalAbsXi;
		
		// Initialize other variables.
		MAXITER = 2 * (W + H);
		rho_s_sqr = 0.5 * (Math.cos (Math.PI/W) + Math.cos (Math.PI/H));
		rho_s_sqr = rho_s_sqr * rho_s_sqr;
		omega_over_4 = 0.25;
		iterations = 0;

		long t2 = System.currentTimeMillis();

		// Perform successive overrelaxation.
		do
			{
			totalAbsXi = 0.0;

			// Red half-sweep.
			for (int r = 1; r <= H; ++ r)
				{
				double[] h_rm1 = h[r-1];
				double[] h_r   = h[r];
				double[] h_rp1 = h[r+1];
				boolean[] hotspot_r = hotspot[r];
				for (int c = 1 + (r&1); c <= W; c += 2)
					{
					xi =
						hotspot_r[c] ?
							0.0 :
							h_rm1[c]+h_rp1[c]+h_r[c-1]+h_r[c+1]-4.0*h_r[c];
					totalAbsXi += Math.abs (xi);
					h_r[c] += omega_over_4 * xi;
					}
				}
			omega_over_4 = 0.25 /
				(1.0 - rho_s_sqr * (iterations == 0 ? 0.5 : omega_over_4));

			// Black half-sweep.
			for (int r = 1; r <= H; ++ r)
				{
				double[] h_rm1 = h[r-1];
				double[] h_r   = h[r];
				double[] h_rp1 = h[r+1];
				boolean[] hotspot_r = hotspot[r];
				for (int c = 2 - (r&1); c <= W; c += 2)
					{
					xi =
						hotspot_r[c] ?
							0.0 :
							h_rm1[c]+h_rp1[c]+h_r[c-1]+h_r[c+1]-4.0*h_r[c];
					totalAbsXi += Math.abs (xi);
					h_r[c] += omega_over_4 * xi;
					}
				}
			omega_over_4 = 0.25 / (1.0 - rho_s_sqr * omega_over_4);

			++ iterations;
			}
		while (iterations < MAXITER && totalAbsXi >= EPS_initialTotalAbsXi);

		// Check for convergence.
		if (iterations == MAXITER)
			{
			System.err.println ("HotSpotSeq: Did not converge");
			System.exit (1);
			}

		long t3 = System.currentTimeMillis();

		// Generate image.
		int[][] matrix = new int [H+2] [W+2];
		ColorImageRow matrix_r = new ColorImageRow (matrix[0]);
		for (int r = 0; r <= H+1; ++ r)
			{
			double[] h_r = h[r];
			matrix_r.setArray (matrix[r]);
			for (int c = 0; c <= W+1; ++ c)
				{
				matrix_r.setPixelHSB
					(/*c  */ c,
					 /*hue*/ (float)
						((h_r[c]-MIN_TEMP)/DELTA_TEMP*DELTA_HUE+MIN_HUE),
					 /*sat*/ 1.0f,
					 /*bri*/ 1.0f);
				}
			}
		PJGHueImage image = new PJGHueImage (H+2, W+2, matrix);
		PJGImage.Writer writer =
			image.prepareToWrite
				(new BufferedOutputStream
					(new FileOutputStream (imagefile)));
		writer.write();
		writer.close();

		// Stop timing.
		long t4 = System.currentTimeMillis();
		System.out.println (iterations + " iterations");
		System.out.println ((t2-t1) + " msec pre");
		System.out.println ((t3-t2) + " msec calc");
		System.out.println ((t4-t3) + " msec post");
		System.out.println ((t4-t1) + " msec total");
		}

// Hidden operations.

	/**
	 * Print a usage message and exit.
	 */
	private static void usage()
		{
		System.err.println ("Usage: java edu.rit.clu.heat.HotSpotSeq <imagefile> <H> <W> <rl1> <cl1> <ru1> <cu1> <temp1> [ <rl2> <cl2> <ru2> <cu2> <temp2> . . . ]");
		System.err.println ("<imagefile> = Output image file name");
		System.err.println ("<H> = Mesh height in pixels (<H> >= 1)");
		System.err.println ("<W> = Mesh width in pixels (<W> >= 1)");
		System.err.println ("<rl1> = First hot spot lower row (1 <= <rl1> <= <W>)");
		System.err.println ("<cl1> = First hot spot lower column (1 <= <cl1> <= <H>)");
		System.err.println ("<ru1> = First hot spot upper row (1 <= <ru1> <= <W>)");
		System.err.println ("<cu1> = First hot spot upper column (1 <= <cu1> <= <H>)");
		System.err.println ("<temp1> = First hot spot temperature (0.0 <= <temp1> <= 100.0)");
		System.exit (1);
		}

	}