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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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// Jacobi iteration on a mesh. Based loosely on a Filaments demo |
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import java.util.concurrent.*; |
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//import jsr166y.*; |
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public class FJJacobi { |
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static final int DEFAULT_GRANULARITY = 4096; // 1024; |
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// static final int DEFAULT_GRANULARITY = 4096; |
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static final int DEFAULT_GRANULARITY = 256; |
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/** |
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* The maximum number of matrix cells |
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* at which to stop recursing down and instead directly update. |
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**/ |
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*/ |
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static final double EPSILON = 0.0001; // convergence criterion |
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public static void main(String[] args) throws Exception { |
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double[][] a = new double[dim][dim]; |
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double[][] b = new double[dim][dim]; |
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// Initialize interiors to small value |
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double smallVal = 1.0/dim; |
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double smallVal = EPSILON; // 1.0/dim; |
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for (int i = 1; i < dim-1; ++i) { |
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for (int j = 1; j < dim-1; ++j) |
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a[i][j] = smallVal; |
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} |
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int nreps = 3; |
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// Fill all edges with 1's. |
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for (int k = 0; k < dim; ++k) { |
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a[k][0] = 1.0; |
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a[k][n+1] = 1.0; |
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a[0][k] = 1.0; |
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a[n+1][k] = 1.0; |
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b[k][0] = 1.0; |
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b[k][n+1] = 1.0; |
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b[0][k] = 1.0; |
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b[n+1][k] = 1.0; |
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} |
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int nreps = 10; |
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for (int rep = 0; rep < nreps; ++rep) { |
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// Fill all edges with 1's. |
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for (int k = 0; k < dim; ++k) { |
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a[k][0] += 1.0; |
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a[k][n+1] += 1.0; |
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a[0][k] += 1.0; |
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a[n+1][k] += 1.0; |
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} |
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Driver driver = new Driver(a, b, 1, n, 1, n, steps, granularity); |
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long startTime = System.currentTimeMillis(); |
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fjp.invoke(driver); |
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long time = System.currentTimeMillis() - startTime; |
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double secs = (double) time / 1000.0; |
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double secs = ((double)time) / 1000.0; |
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System.out.println("Compute Time: " + secs); |
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System.out.println("Workers: " + fjp.getPoolSize()); |
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System.out.println(fjp); |
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} |
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} |
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abstract static class MatrixTree extends RecursiveAction { |
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// maximum difference between old and new values |
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double maxDiff; |
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if (tryUnfork()) |
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compute(); |
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else { |
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// quietlyJoin(); |
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quietlyHelpJoin(); |
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quietlyJoin(); |
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reinitialize(); |
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} |
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double m = maxDiff; |
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return (md > m) ? md : m; |
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} |
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} |
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static final class LeafNode extends MatrixTree { |
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final double[][] A; // matrix to get old values from |
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final double[][] B; // matrix to put new values into |
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} |
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} |
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static final class TwoNode extends MatrixTree { |
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final MatrixTree q1; |
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final MatrixTree q2; |
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} |
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static final class Driver extends RecursiveAction { |
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MatrixTree mat; |
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double[][] A; double[][] B; |
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System.out.println("max diff after " + steps + " steps = " + md); |
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} |
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} |
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} |
