How to use

binomialCoefficientLog

method

in

org.matheclipse.parser.client.math.MathUtils

/**
 * Returns a <code>double</code> representation of the
 * <a href="http://mathworld.wolfram.com/BinomialCoefficient.html"> Binomial
 * Coefficient</a>, "<code>n choose k</code>", the number of
 * <code>k</code>-element subsets that can be selected from an
 * <code>n</code>-element set.
 * 
 * <Strong>Preconditions</strong>:
 * <ul>
 * <li><code>0 &lt;= k &lt;= n </code> (otherwise
 * <code>IllegalArgumentException</code> is thrown)</li>
 * <li>The result is small enough to fit into a <code>double</code>. The
 * largest value of <code>n</code> for which all coefficients are &lt;
 * Double.MAX_VALUE is 1029. If the computed value exceeds Double.MAX_VALUE,
 * Double.POSITIVE_INFINITY is returned</li>
 * </ul>
 * 
 * @param n the size of the set
 * @param k the size of the subsets to be counted
 * @return <code>n choose k</code>
 * @throws java.lang.IllegalArgumentException if preconditions are not met.
 */
public static double binomialCoefficientDouble( final int n, final int k ) {
  return Math.floor( Math.exp( binomialCoefficientLog( n, k ) ) + 0.5 );
}

/**
 * Returns a <code>double</code> representation of the <a
 * href="http://mathworld.wolfram.com/BinomialCoefficient.html"> Binomial
 * Coefficient</a>, "<code>n choose k</code>", the number of
 * <code>k</code>-element subsets that can be selected from an
 * <code>n</code>-element set.
 * <p>
 * <Strong>Preconditions</strong>:
 * <ul>
 * <li> <code>0 <= k <= n </code> (otherwise
 * <code>IllegalArgumentException</code> is thrown)</li>
 * <li> The result is small enough to fit into a <code>double</code>. The
 * largest value of <code>n</code> for which all coefficients are <
 * Double.MAX_VALUE is 1029. If the computed value exceeds Double.MAX_VALUE,
 * Double.POSITIVE_INFINITY is returned</li>
 * </ul>
 * </p>
 * 
 * @param n
 *          the size of the set
 * @param k
 *          the size of the subsets to be counted
 * @return <code>n choose k</code>
 * @throws IllegalArgumentException
 *           if preconditions are not met.
 */
public static double binomialCoefficientDouble(final int n, final int k) {
  return Math.floor(Math.exp(binomialCoefficientLog(n, k)) + 0.5);
}

/**
 * Returns a <code>double</code> representation of the <a
 * href="http://mathworld.wolfram.com/BinomialCoefficient.html"> Binomial
 * Coefficient</a>, "<code>n choose k</code>", the number of
 * <code>k</code>-element subsets that can be selected from an
 * <code>n</code>-element set.
 * <p>
 * <Strong>Preconditions</strong>:
 * <ul>
 * <li> <code>0 <= k <= n </code> (otherwise
 * <code>IllegalArgumentException</code> is thrown)</li>
 * <li> The result is small enough to fit into a <code>double</code>. The
 * largest value of <code>n</code> for which all coefficients are <
 * Double.MAX_VALUE is 1029. If the computed value exceeds Double.MAX_VALUE,
 * Double.POSITIVE_INFINITY is returned</li>
 * </ul>
 * </p>
 * 
 * @param n
 *          the size of the set
 * @param k
 *          the size of the subsets to be counted
 * @return <code>n choose k</code>
 * @throws IllegalArgumentException
 *           if preconditions are not met.
 */
public static double binomialCoefficientDouble(final int n, final int k) {
  return Math.floor(Math.exp(binomialCoefficientLog(n, k)) + 0.5);
}