optimized some fraction operations (mainly pow)
replaced pow(BigFraction) by pow(double) as it already converted the argument to double upon entry added tests for pow git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@760016 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Luc Maisonobe
parent
40223343f0
commit
80419081ac
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@ -20,6 +20,7 @@ import java.math.BigDecimal;
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import java.math.BigInteger;
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import org.apache.commons.math.MathRuntimeException;
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import org.apache.commons.math.util.MathUtils;
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/**
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* Representation of a rational number without any overflow. This class is
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@ -457,7 +458,35 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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* if the {@link BigInteger} is <code>null</code>.
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*/
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public BigFraction add(final BigInteger bg) {
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return add(new BigFraction(bg, BigInteger.ONE));
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return new BigFraction(numerator.add(denominator.multiply(bg)), denominator);
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}
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/**
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* <p>
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* Adds the value of this fraction to the passed <tt>integer</tt>, returning
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* the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>integer</tt> to add.
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* @return a <code>BigFraction</code> instance with the resulting values.
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*/
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public BigFraction add(final int i) {
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return add(BigInteger.valueOf(i));
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}
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/**
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* <p>
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* Adds the value of this fraction to the passed <tt>long</tt>, returning
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* the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to add.
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* @return a <code>BigFraction</code> instance with the resulting values.
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*/
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public BigFraction add(final long l) {
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return add(BigInteger.valueOf(l));
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}
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/**
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@ -491,34 +520,6 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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}
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/**
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* <p>
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* Adds the value of this fraction to the passed <tt>integer</tt>, returning
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* the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>integer</tt> to add.
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* @return a <code>BigFraction</code> instance with the resulting values.
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*/
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public BigFraction add(final int i) {
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return add(new BigFraction(i, 1));
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}
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/**
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* <p>
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* Adds the value of this fraction to the passed <tt>long</tt>, returning
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* the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to add.
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* @return a <code>BigFraction</code> instance with the resulting values.
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*/
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public BigFraction add(final long l) {
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return add(new BigFraction(l, 1L));
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}
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/**
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* <p>
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* Gets the fraction as a <code>BigDecimal</code>. This calculates the
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@ -602,9 +603,46 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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* @return a {@link BigFraction} instance with the resulting values.
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* @throws NullPointerException
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* if the <code>BigInteger</code> is <code>null</code>.
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* @throws ArithmeticException
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* if the fraction to divide by is zero.
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*/
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public BigFraction divide(final BigInteger bg) {
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return divide(new BigFraction(bg, BigInteger.ONE));
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if (BigInteger.ZERO.equals(bg)) {
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throw MathRuntimeException.createArithmeticException("denominator must be different from 0");
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}
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return new BigFraction(numerator, denominator.multiply(bg));
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}
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/**
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* <p>
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* Divide the value of this fraction by the passed <tt>int</tt>, ie
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* "this * 1 / i", returning the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>int</tt> to divide by.
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* @return a {@link BigFraction} instance with the resulting values.
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* @throws ArithmeticException
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* if the fraction to divide by is zero.
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*/
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public BigFraction divide(final int i) {
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return divide(BigInteger.valueOf(i));
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}
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/**
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* <p>
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* Divide the value of this fraction by the passed <tt>long</tt>, ie
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* "this * 1 / l", returning the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to divide by.
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* @return a {@link BigFraction} instance with the resulting values.
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* @throws ArithmeticException
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* if the fraction to divide by is zero.
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*/
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public BigFraction divide(final long l) {
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return divide(BigInteger.valueOf(l));
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}
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/**
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@ -629,34 +667,6 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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return multiply(fraction.reciprocal());
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}
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/**
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* <p>
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* Divide the value of this fraction by the passed <tt>int</tt>, ie
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* "this * 1 / i", returning the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>int</tt> to divide by.
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* @return a {@link BigFraction} instance with the resulting values.
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*/
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public BigFraction divide(final int i) {
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return divide(new BigFraction(i, 1));
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}
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/**
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* <p>
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* Divide the value of this fraction by the passed <tt>long</tt>, ie
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* "this * 1 / l", returning the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to divide by.
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* @return a {@link BigFraction} instance with the resulting values.
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*/
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public BigFraction divide(final long l) {
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return divide(new BigFraction(l, 1L));
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}
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/**
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* <p>
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* Gets the fraction as a <tt>double</tt>. This calculates the fraction as
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@ -838,6 +848,34 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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return new BigFraction(bg.multiply(numerator), denominator);
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}
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/**
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* <p>
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* Multiply the value of this fraction by the passed <tt>int</tt>, returning
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* the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>int</tt> to multiply by.
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* @return a {@link BigFraction} instance with the resulting values.
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*/
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public BigFraction multiply(final int i) {
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return multiply(BigInteger.valueOf(i));
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}
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/**
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* <p>
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* Multiply the value of this fraction by the passed <tt>long</tt>,
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* returning the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to multiply by.
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* @return a {@link BigFraction} instance with the resulting values.
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*/
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public BigFraction multiply(final long l) {
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return multiply(BigInteger.valueOf(l));
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}
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/**
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* <p>
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* Multiplies the value of this fraction by another, returning the result in
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@ -860,34 +898,6 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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return ret;
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}
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/**
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* <p>
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* Multiply the value of this fraction by the passed <tt>int</tt>, returning
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* the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>int</tt> to multiply by.
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* @return a {@link BigFraction} instance with the resulting values.
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*/
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public BigFraction multiply(final int i) {
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return multiply(new BigFraction(i, 1));
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}
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/**
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* <p>
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* Multiply the value of this fraction by the passed <tt>long</tt>,
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* returning the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to multiply by.
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* @return a {@link BigFraction} instance with the resulting values.
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*/
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public BigFraction multiply(final long l) {
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return multiply(new BigFraction(l, 1L));
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}
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/**
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* <p>
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* Return the additive inverse of this fraction, returning the result in
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@ -912,44 +922,6 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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return (numerator.divide(denominator)).multiply(ONE_HUNDRED_DOUBLE).doubleValue();
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}
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/**
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* <p>
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* Returns a <code>BigFraction</code> whose value is
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* <tt>(this<sup>exponent</sup>)</tt>, returning the result in reduced form.
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* </p>
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*
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* @param exponent
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* exponent to which this <code>BigFraction</code> is to be raised.
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* @return <tt>this<sup>exponent</sup></tt> as a <code>BigFraction</code>.
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*/
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public BigFraction pow(final BigInteger exponent) {
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BigFraction ret = this;
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if (!BigInteger.ONE.equals(exponent)) {
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ret = ONE;
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if (!BigInteger.ZERO.equals(exponent)) {
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for (BigInteger bg = BigInteger.ONE; bg.compareTo(exponent) < 0; bg = bg.add(BigInteger.ONE)) {
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ret = ret.multiply(this);
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}
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}
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}
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return ret;
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}
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/**
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* <p>
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* Returns a <code>BigFraction</code> whose value is
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* <tt>(this<sup>exponent</sup>)</tt>, returning the result in reduced form.
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* </p>
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*
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* @param exponent
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* exponent to which this <code>BigFraction</code> is to be raised.
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* @return <tt>this<sup>exponent</sup></tt>.
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*/
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public double pow(final BigFraction exponent) {
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return Math.pow(numerator.doubleValue(), exponent.doubleValue()) / Math.pow(denominator.doubleValue(), exponent.doubleValue());
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}
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/**
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* <p>
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* Returns a <tt>integer</tt> whose value is
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@ -962,7 +934,10 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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* @return <tt>this<sup>exponent</sup></tt>.
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*/
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public BigFraction pow(final int exponent) {
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return pow(BigInteger.valueOf(exponent));
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if (exponent < 0) {
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return new BigFraction(denominator.pow(-exponent), numerator.pow(-exponent));
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}
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return new BigFraction(numerator.pow(exponent), denominator.pow(exponent));
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}
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/**
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@ -976,7 +951,47 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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* @return <tt>this<sup>exponent</sup></tt> as a <code>BigFraction</code>.
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*/
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public BigFraction pow(final long exponent) {
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return pow(BigInteger.valueOf(exponent));
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if (exponent < 0) {
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return new BigFraction(MathUtils.pow(denominator, -exponent),
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MathUtils.pow(numerator, -exponent));
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}
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return new BigFraction(MathUtils.pow(numerator, exponent),
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MathUtils.pow(denominator, exponent));
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}
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/**
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* <p>
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* Returns a <code>BigFraction</code> whose value is
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* <tt>(this<sup>exponent</sup>)</tt>, returning the result in reduced form.
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* </p>
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*
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* @param exponent
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* exponent to which this <code>BigFraction</code> is to be raised.
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* @return <tt>this<sup>exponent</sup></tt> as a <code>BigFraction</code>.
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*/
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public BigFraction pow(final BigInteger exponent) {
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if (exponent.compareTo(BigInteger.ZERO) < 0) {
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final BigInteger eNeg = exponent.negate();
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return new BigFraction(MathUtils.pow(denominator, eNeg),
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MathUtils.pow(numerator, eNeg));
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}
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return new BigFraction(MathUtils.pow(numerator, exponent),
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MathUtils.pow(denominator, exponent));
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}
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/**
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* <p>
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* Returns a <code>double</code> whose value is
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* <tt>(this<sup>exponent</sup>)</tt>, returning the result in reduced form.
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* </p>
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*
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* @param exponent
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* exponent to which this <code>BigFraction</code> is to be raised.
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* @return <tt>this<sup>exponent</sup></tt>.
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*/
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public double pow(final double exponent) {
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return Math.pow(numerator.doubleValue(), exponent) /
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Math.pow(denominator.doubleValue(), exponent);
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}
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/**
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@ -1017,7 +1032,36 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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* if the {@link BigInteger} is <code>null</code>.
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*/
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public BigFraction subtract(final BigInteger bg) {
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return subtract(new BigFraction(bg, BigInteger.valueOf(1)));
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return new BigFraction(numerator.subtract(denominator.multiply(bg)), denominator);
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}
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/**
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* <p>
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* Subtracts the value of an <tt>integer</tt> from the value of this one,
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* returning the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>integer</tt> to subtract.
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* @return a <code>BigFraction</code> instance with the resulting values.
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*/
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public BigFraction subtract(final int i) {
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return subtract(BigInteger.valueOf(i));
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}
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/**
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* <p>
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* Subtracts the value of an <tt>integer</tt> from the value of this one,
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* returning the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to subtract.
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* @return a <code>BigFraction</code> instance with the resulting values, or
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* this object if the <tt>long</tt> is zero.
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*/
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public BigFraction subtract(final long l) {
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return subtract(BigInteger.valueOf(l));
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}
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/**
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@ -1051,35 +1095,6 @@ public class BigFraction extends Number implements Comparable<BigFraction> {
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}
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/**
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* <p>
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* Subtracts the value of an <tt>integer</tt> from the value of this one,
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* returning the result in reduced form.
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* </p>
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*
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* @param i
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* the <tt>integer</tt> to subtract.
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* @return a <code>BigFraction</code> instance with the resulting values.
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*/
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public BigFraction subtract(final int i) {
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return subtract(new BigFraction(i, 1));
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}
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/**
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* <p>
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* Subtracts the value of an <tt>integer</tt> from the value of this one,
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* returning the result in reduced form.
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* </p>
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*
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* @param l
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* the <tt>long</tt> to subtract.
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* @return a <code>BigFraction</code> instance with the resulting values, or
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* this object if the <tt>long</tt> is zero.
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*/
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public BigFraction subtract(final long l) {
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return subtract(new BigFraction(l, 1L));
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}
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/**
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* <p>
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* Returns the <code>String</code> representing this fraction, ie
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@ -537,4 +537,17 @@ public class BigFractionTest extends TestCase {
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assertEquals(BigFraction.getReducedFraction(2, Integer.MIN_VALUE).getNumeratorAsInt(), -1);
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assertEquals(BigFraction.getReducedFraction(1, -1).getNumeratorAsInt(), -1);
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}
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public void testPow() {
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assertEquals(new BigFraction(8192, 1594323), new BigFraction(2, 3).pow(13));
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assertEquals(new BigFraction(8192, 1594323), new BigFraction(2, 3).pow(13l));
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assertEquals(new BigFraction(8192, 1594323), new BigFraction(2, 3).pow(BigInteger.valueOf(13l)));
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assertEquals(BigFraction.ONE, new BigFraction(2, 3).pow(0));
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assertEquals(BigFraction.ONE, new BigFraction(2, 3).pow(0l));
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assertEquals(BigFraction.ONE, new BigFraction(2, 3).pow(BigInteger.valueOf(0l)));
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assertEquals(new BigFraction(1594323, 8192), new BigFraction(2, 3).pow(-13));
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assertEquals(new BigFraction(1594323, 8192), new BigFraction(2, 3).pow(-13l));
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assertEquals(new BigFraction(1594323, 8192), new BigFraction(2, 3).pow(BigInteger.valueOf(-13l)));
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}
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}
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