Percolation/Mean run density: Difference between revisions
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500 0.90 4096 0.090 0.090 0.1
500 0.90 16384 0.090 0.090 0.1
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=={{header|Java}}==
<syntaxhighlight lang="java">
import java.util.concurrent.ThreadLocalRandom;
public final class PercolationMeanRun {
public static void main(String[] aArgs) {
System.out.println("Running 1000 tests each:" + System.lineSeparator());
System.out.println(" p\tlength\tresult\ttheory\t difference");
System.out.println("-".repeat(48));
for ( double probability = 0.1; probability <= 0.9; probability += 0.2 ) {
double theory = probability * ( 1.0 - probability );
int length = 100;
while ( length <= 100_000 ) {
double result = runTest(probability, length, 1_000);
System.out.println(String.format("%.1f\t%6d\t%.4f\t%.4f\t%+.4f (%+.2f%%)",
probability, length, result, theory, result - theory, ( result - theory ) / theory * 100));
length *= 10;
}
System.out.println();
}
}
private static double runTest(double aProbability, int aLength, int aRunCount) {
double count = 0.0;
final int threshold = (int) ( aProbability * RANDOM_MAXIMUM );
for ( int run = 0; run < aRunCount; run++ ) {
int previousBit = 0;
int length = aLength;
while ( length-- > 0 ) {
int nextBit = ( RANDOM.nextInt(RANDOM_MAXIMUM + 1) < threshold ) ? 1 : 0;
if ( previousBit < nextBit ) {
count += 1.0;
}
previousBit = nextBit;
}
}
return count / aRunCount / aLength;
}
private static ThreadLocalRandom RANDOM = ThreadLocalRandom.current();
private static final int RANDOM_MAXIMUM = Integer.MAX_VALUE - 1;
}
</syntaxhighlight>
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<pre>
Running 1000 tests each:
p length result theory difference
------------------------------------------------
0.1 100 0.0899 0.0900 -0.0001 (-0.07%)
0.1 1000 0.0902 0.0900 +0.0002 (+0.18%)
0.1 10000 0.0900 0.0900 +0.0000 (+0.02%)
0.1 100000 0.0900 0.0900 -0.0000 (-0.00%)
0.3 100 0.2110 0.2100 +0.0010 (+0.47%)
0.3 1000 0.2101 0.2100 +0.0001 (+0.05%)
0.3 10000 0.2100 0.2100 -0.0000 (-0.01%)
0.3 100000 0.2100 0.2100 -0.0000 (-0.01%)
0.5 100 0.2516 0.2500 +0.0015 (+0.62%)
0.5 1000 0.2509 0.2500 +0.0009 (+0.37%)
0.5 10000 0.2499 0.2500 -0.0001 (-0.04%)
0.5 100000 0.2500 0.2500 +0.0000 (+0.00%)
0.7 100 0.2145 0.2100 +0.0045 (+2.12%)
0.7 1000 0.2106 0.2100 +0.0006 (+0.28%)
0.7 10000 0.2101 0.2100 +0.0001 (+0.06%)
0.7 100000 0.2100 0.2100 -0.0000 (-0.00%)
0.9 100 0.0970 0.0900 +0.0070 (+7.74%)
0.9 1000 0.0910 0.0900 +0.0010 (+1.15%)
0.9 10000 0.0901 0.0900 +0.0001 (+0.06%)
0.9 100000 0.0900 0.0900 +0.0000 (+0.00%)
</pre>
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