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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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jsr166 |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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import java.util.concurrent.*; |
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/** |
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* Sample program using Guassian Quadrature for numerical integration. |
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* This version uses a simplified hardwired function. Inspired by a |
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* <A href="http://www.cs.uga.edu/~dkl/filaments/dist.html"> |
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* Filaments</A> demo program. |
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*/ |
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public final class Integrate { |
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static final double errorTolerance = 1.0e-12; |
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/** for time conversion */ |
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static final long NPS = (1000L * 1000 * 1000); |
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static final int SERIAL = -1; |
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static final int DYNAMIC = 0; |
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static final int FORK = 1; |
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static int forkPolicy = DYNAMIC; |
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static String forkArg = "dynamic"; |
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/** the function to integrate */ |
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static double computeFunction(double x) { |
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return (x * x + 1.0) * x; |
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} |
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static final double start = 0.0; |
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static final double end = 1536.0; |
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/** |
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* The number of recursive calls for |
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* integrate from start to end. |
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* (Empirically determined) |
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*/ |
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static final int calls = 263479047; |
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public static void main(String[] args) throws Exception { |
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int procs = 0; |
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try { |
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if (args.length > 0) |
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procs = Integer.parseInt(args[0]); |
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if (args.length > 1) { |
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forkArg = args[1]; |
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if (forkArg.startsWith("s")) |
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forkPolicy = SERIAL; |
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else if (forkArg.startsWith("f")) |
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forkPolicy = FORK; |
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} |
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} |
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catch (Exception e) { |
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System.out.println("Usage: java Integrate3 threads <s[erial] | d[ynamic] | f[ork] - default d>"); |
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return; |
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} |
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oneTest(procs); |
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oneTest(procs); |
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oneTest(procs); |
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} |
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|
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static void oneTest(int procs) { |
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jsr166 |
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ForkJoinPool g = (procs == 0) ? new ForkJoinPool() : |
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new ForkJoinPool(procs); |
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System.out.println("Number of procs=" + g.getParallelism()); |
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System.out.println("Integrating from " + start + " to " + end + |
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" forkPolicy = " + forkArg); |
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long lastTime = System.nanoTime(); |
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for (int i = 0; i < 20; ++i) { |
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double a; |
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if (forkPolicy == SERIAL) |
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a = SQuad.computeArea(g, start, end); |
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else if (forkPolicy == FORK) |
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a = FQuad.computeArea(g, start, end); |
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else |
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a = DQuad.computeArea(g, start, end); |
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long now = System.nanoTime(); |
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double s = ((double)(now - lastTime))/NPS; |
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lastTime = now; |
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System.out.printf("Calls/sec: %12d", (long) (calls / s)); |
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System.out.printf(" Time: %7.3f", s); |
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System.out.printf(" Threads: %5d", g.getPoolSize()); |
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// System.out.printf(" Area: %12.1f", a); |
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System.out.println(); |
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} |
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System.out.println(g); |
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g.shutdown(); |
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} |
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// Sequential version |
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static final class SQuad extends RecursiveAction { |
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static double computeArea(ForkJoinPool pool, double l, double r) { |
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SQuad q = new SQuad(l, r, 0); |
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pool.invoke(q); |
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return q.area; |
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} |
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final double left; // lower bound |
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final double right; // upper bound |
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double area; |
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SQuad(double l, double r, double a) { |
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this.left = l; this.right = r; this.area = a; |
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} |
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public final void compute() { |
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double l = left; |
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double r = right; |
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area = recEval(l, r, (l * l + 1.0) * l, (r * r + 1.0) * r, area); |
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} |
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static final double recEval(double l, double r, double fl, |
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double fr, double a) { |
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double h = (r - l) * 0.5; |
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double c = l + h; |
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double fc = (c * c + 1.0) * c; |
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double hh = h * 0.5; |
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double al = (fl + fc) * hh; |
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double ar = (fr + fc) * hh; |
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double alr = al + ar; |
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if (Math.abs(alr - a) <= errorTolerance) |
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return alr; |
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else |
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return recEval(c, r, fc, fr, ar) + recEval(l, c, fl, fc, al); |
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} |
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} |
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//.................................... |
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// ForkJoin version |
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static final class FQuad extends RecursiveAction { |
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static double computeArea(ForkJoinPool pool, double l, double r) { |
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FQuad q = new FQuad(l, r, 0); |
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pool.invoke(q); |
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return q.area; |
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} |
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final double left; // lower bound |
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final double right; // upper bound |
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double area; |
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FQuad(double l, double r, double a) { |
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this.left = l; this.right = r; this.area = a; |
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} |
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public final void compute() { |
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double l = left; |
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double r = right; |
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area = recEval(l, r, (l * l + 1.0) * l, (r * r + 1.0) * r, area); |
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} |
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|
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static final double recEval(double l, double r, double fl, |
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double fr, double a) { |
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double h = (r - l) * 0.5; |
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double c = l + h; |
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jsr166 |
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double fc = (c * c + 1.0) * c; |
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double hh = h * 0.5; |
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double al = (fl + fc) * hh; |
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double ar = (fr + fc) * hh; |
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double alr = al + ar; |
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if (Math.abs(alr - a) <= errorTolerance) |
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return alr; |
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FQuad q = new FQuad(l, c, al); |
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q.fork(); |
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ar = recEval(c, r, fc, fr, ar); |
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if (!q.tryUnfork()) { |
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q.quietlyJoin(); |
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return ar + q.area; |
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} |
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return ar + recEval(l, c, fl, fc, al); |
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} |
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} |
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// ........................... |
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1.9 |
// Version using on-demand Fork |
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static final class DQuad extends RecursiveAction { |
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static double computeArea(ForkJoinPool pool, double l, double r) { |
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DQuad q = new DQuad(l, r, 0); |
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pool.invoke(q); |
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return q.area; |
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} |
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final double left; // lower bound |
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final double right; // upper bound |
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double area; |
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DQuad(double l, double r, double a) { |
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this.left = l; this.right = r; this.area = a; |
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} |
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public final void compute() { |
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double l = left; |
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double r = right; |
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area = recEval(l, r, (l * l + 1.0) * l, (r * r + 1.0) * r, area); |
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} |
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static final double recEval(double l, double r, double fl, |
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double fr, double a) { |
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double h = (r - l) * 0.5; |
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double c = l + h; |
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double fc = (c * c + 1.0) * c; |
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double hh = h * 0.5; |
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double al = (fl + fc) * hh; |
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double ar = (fr + fc) * hh; |
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double alr = al + ar; |
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if (Math.abs(alr - a) <= errorTolerance) |
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return alr; |
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DQuad q = null; |
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if (getSurplusQueuedTaskCount() <= 3) |
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(q = new DQuad(l, c, al)).fork(); |
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ar = recEval(c, r, fc, fr, ar); |
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if (q != null && !q.tryUnfork()) { |
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q.quietlyJoin(); |
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return ar + q.area; |
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} |
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return ar + recEval(l, c, fl, fc, al); |
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} |
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} |
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} |