Android Open Source - dice-probabilities Failure Special

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License

The source code is released under:

MIT License

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Java Source Code

package org.kleemann.diceprobabilities.special;
/*from   w ww  . j av  a 2  s  .c  o  m*/
import org.apache.commons.math3.fraction.BigFraction;
import org.kleemann.diceprobabilities.distribution.Distribution;
import org.kleemann.diceprobabilities.distribution.ScaleCumulativeDistribution;

import android.util.SparseIntArray;

/**
 * <p>
 * After a successful check, failure still occurs with the given probability.
 */
class FailureSpecial extends AbstractSpecial {

  private BigFraction success;

  public FailureSpecial(String title, String description, BigFraction failure) {
    super(title, description);
    this.success = BigFraction.ONE.subtract(failure);
  }

  @Override
  public Distribution getDistribution(SparseIntArray sidesToCount) {
    Distribution d = super.getDistribution(sidesToCount);

    // we need to adjust the cumulative distribution past it's lower bound
    // all the way to zero since failure always results if a the final
    // success fails rolled.
    // There is no 100% with this distribution.

    return ScaleCumulativeDistribution.scale(d, 0, d.upperBound(),
        new ScaleCumulativeDistribution.Scale() {
          public BigFraction scale(BigFraction pS, int x) {
            // P(S) = 1 - P(F)
            // P(new) = (1/6) * 0 + (5/6) * P(S)
            // P(new) = (5/6) * P(S)
            return success.multiply(pS);
          }
        });

  }
}

Java Source Code List