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Moved o.a.c.m.transform.FastFourierTransformer.isPowerOf2 to o.a.c.m.util.ArithmeticUtils.isPowerOfTwo (MATH-677). 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1227042 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Sebastien Brisard 2012-01-04 03:47:46 +00:00
parent 7f6912730e
commit a4d7e7c86d
5 changed files with 33 additions and 17 deletions
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3
src/main/java/org/apache/commons/math/transform/FastCosineTransformer.java
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@ -22,6 +22,7 @@ import org.apache.commons.math.exception.MathIllegalArgumentException;
import org.apache.commons.math.exception.NonMonotonicSequenceException;
import org.apache.commons.math.exception.NotStrictlyPositiveException;
import org.apache.commons.math.exception.util.LocalizedFormats;
import org.apache.commons.math.util.ArithmeticUtils;
import org.apache.commons.math.util.FastMath;
/**
@ -238,7 +239,7 @@ public class FastCosineTransformer implements RealTransformer {
final double[] transformed = new double[f.length];
final int n = f.length - 1;
if (!FastFourierTransformer.isPowerOf2(n)) {
if (!ArithmeticUtils.isPowerOfTwo(n)) {
throw new MathIllegalArgumentException(
LocalizedFormats.NOT_POWER_OF_TWO_PLUS_ONE,
Integer.valueOf(f.length));

15
src/main/java/org/apache/commons/math/transform/FastFourierTransformer.java
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@ -29,6 +29,7 @@ import org.apache.commons.math.exception.NotStrictlyPositiveException;
import org.apache.commons.math.exception.OutOfRangeException;
import org.apache.commons.math.exception.ZeroException;
import org.apache.commons.math.exception.util.LocalizedFormats;
import org.apache.commons.math.util.ArithmeticUtils;
import org.apache.commons.math.util.FastMath;
/**
@ -465,16 +466,6 @@ public class FastFourierTransformer implements Serializable {
return f;
}
/**
* Returns true if the argument is a power of 2.
*
* @param n the number to test
* @return true if the argument is a power of 2
*/
public static boolean isPowerOf2(long n) {
return (n > 0) && ((n & (n - 1)) == 0);
}
/**
* Verifies that the data set has length of power of 2.
*
@ -484,7 +475,7 @@ public class FastFourierTransformer implements Serializable {
public static void verifyDataSet(double[] d)
throws MathIllegalArgumentException {
if (!isPowerOf2(d.length)) {
if (!ArithmeticUtils.isPowerOfTwo(d.length)) {
throw new MathIllegalArgumentException(
LocalizedFormats.NOT_POWER_OF_TWO_CONSIDER_PADDING,
Integer.valueOf(d.length));
@ -500,7 +491,7 @@ public class FastFourierTransformer implements Serializable {
public static void verifyDataSet(Object[] o)
throws MathIllegalArgumentException {
if (!isPowerOf2(o.length)) {
if (!ArithmeticUtils.isPowerOfTwo(o.length)) {
throw new MathIllegalArgumentException(
LocalizedFormats.NOT_POWER_OF_TWO_CONSIDER_PADDING,
Integer.valueOf(o.length));

5
src/main/java/org/apache/commons/math/transform/FastHadamardTransformer.java
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@ -21,6 +21,7 @@ import org.apache.commons.math.exception.MathIllegalArgumentException;
import org.apache.commons.math.exception.NonMonotonicSequenceException;
import org.apache.commons.math.exception.NotStrictlyPositiveException;
import org.apache.commons.math.exception.util.LocalizedFormats;
import org.apache.commons.math.util.ArithmeticUtils;
/**
* Implements the <a href="http://www.archive.chipcenter.com/dsp/DSP000517F1.html">Fast Hadamard Transform</a> (FHT).
@ -259,7 +260,7 @@ public class FastHadamardTransformer implements RealTransformer {
final int n = x.length;
final int halfN = n / 2;
if (!FastFourierTransformer.isPowerOf2(n)) {
if (!ArithmeticUtils.isPowerOfTwo(n)) {
throw new MathIllegalArgumentException(
LocalizedFormats.NOT_POWER_OF_TWO,
Integer.valueOf(n));
@ -311,7 +312,7 @@ public class FastHadamardTransformer implements RealTransformer {
final int n = x.length;
final int halfN = n / 2;
if (!FastFourierTransformer.isPowerOf2(n)) {
if (!ArithmeticUtils.isPowerOfTwo(n)) {
throw new MathIllegalArgumentException(
LocalizedFormats.NOT_POWER_OF_TWO,
Integer.valueOf(n));

11
src/main/java/org/apache/commons/math/util/ArithmeticUtils.java
View File

@ -18,7 +18,6 @@ package org.apache.commons.math.util;
import java.math.BigInteger;
import org.apache.commons.math.exception.MathArithmeticException;
import org.apache.commons.math.exception.MathIllegalNumberException;
import org.apache.commons.math.exception.NotPositiveException;
import org.apache.commons.math.exception.NumberIsTooLargeException;
import org.apache.commons.math.exception.util.Localizable;
@ -943,4 +942,14 @@ public final class ArithmeticUtils {
throw new NotPositiveException(LocalizedFormats.BINOMIAL_NEGATIVE_PARAMETER, n);
}
}
/**
* Returns true if the argument is a power of two.
*
* @param n the number to test
* @return true if the argument is a power of two
*/
public static boolean isPowerOfTwo(long n) {
return (n > 0) && ((n & (n - 1)) == 0);
}
}

16
src/test/java/org/apache/commons/math/util/ArithmeticUtilsTest.java
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@ -17,6 +17,7 @@
package org.apache.commons.math.util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@ -678,6 +679,20 @@ public class ArithmeticUtilsTest {
}
@Test
public void testIsPowerOfTwo() {
final int n = 1025;
final boolean[] expected = new boolean[n];
Arrays.fill(expected, false);
for (int i = 1; i < expected.length; i *= 2) {
expected[i] = true;
}
for (int i = 0; i < expected.length; i++) {
final boolean actual = ArithmeticUtils.isPowerOfTwo(i);
Assert.assertTrue(Integer.toString(i), actual == expected[i]);
}
}
/**
* Exact (caching) recursive implementation to test against
*/
@ -750,6 +765,5 @@ public class ArithmeticUtilsTest {
} catch (MathArithmeticException ex) {
// success
}
}
}