Author: luc
Date: Sun Oct 26 07:55:45 2008
New Revision: 708001
URL: http://svn.apache.org/viewvc?rev=708001&view=rev
Log:
Added a scalb method in MathUtils.
This method is similar to the method with same name added in java.lang.Math as
of Java 6.
Modified:
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/util/MathUtils.java
commons/proper/math/branches/MATH_2_0/src/site/xdoc/changes.xml
commons/proper/math/branches/MATH_2_0/src/test/org/apache/commons/math/util/MathUtilsTest.java
Modified:
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/util/MathUtils.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/util/MathUtils.java?rev=708001&r1=708000&r2=708001&view=diff
==============================================================================
---
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/util/MathUtils.java
(original)
+++
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/util/MathUtils.java
Sun Oct 26 07:55:45 2008
@@ -713,6 +713,33 @@
}
/**
+ * Scale a number by 2<sup>scaleFactor</sup>.
+ * <p>If <code>d</code> is 0 or NaN or Infinite, it is returned
unchanged.</p>
+ *
+ * @param d base number
+ * @param scaleFactor power of two by which d sould be multiplied
+ * @return d × 2<sup>scaleFactor</sup>
+ * @since 2.0
+ */
+ public static double scalb(final double d, final int scaleFactor) {
+
+ // handling of some important special cases
+ if ((d == 0) || Double.isNaN(d) || Double.isInfinite(d)) {
+ return d;
+ }
+
+ // split the double in raw components
+ final long bits = Double.doubleToLongBits(d);
+ final long exponent = bits & 0x7ff0000000000000L;
+ final long rest = bits & 0x800fffffffffffffL;
+
+ // shift the exponent
+ final long newBits = rest | (exponent + (((long) scaleFactor) << 52));
+ return Double.longBitsToDouble(newBits);
+
+ }
+
+ /**
* Normalize an angle in a 2&pi wide interval around a center value.
* <p>This method has three main uses:</p>
* <ul>
Modified: commons/proper/math/branches/MATH_2_0/src/site/xdoc/changes.xml
URL:
http://svn.apache.org/viewvc/commons/proper/math/branches/MATH_2_0/src/site/xdoc/changes.xml?rev=708001&r1=708000&r2=708001&view=diff
==============================================================================
--- commons/proper/math/branches/MATH_2_0/src/site/xdoc/changes.xml (original)
+++ commons/proper/math/branches/MATH_2_0/src/site/xdoc/changes.xml Sun Oct 26
07:55:45 2008
@@ -39,6 +39,10 @@
</properties>
<body>
<release version="2.0" date="TBD" description="TBD">
+ <action dev="luc" type="add" >
+ Added a scalb method in MathUtils. This method is similar to the method
+ with same name added in java.lang.Math as of Java 6.
+ </action>
<action dev="brentworden" type="fix" issue="MATH-227" due-to="Joerg
Henning">
Fixed F distribution inverse CDF computation for small denominator
degrees of freedom.
</action>
Modified:
commons/proper/math/branches/MATH_2_0/src/test/org/apache/commons/math/util/MathUtilsTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/branches/MATH_2_0/src/test/org/apache/commons/math/util/MathUtilsTest.java?rev=708001&r1=708000&r2=708001&view=diff
==============================================================================
---
commons/proper/math/branches/MATH_2_0/src/test/org/apache/commons/math/util/MathUtilsTest.java
(original)
+++
commons/proper/math/branches/MATH_2_0/src/test/org/apache/commons/math/util/MathUtilsTest.java
Sun Oct 26 07:55:45 2008
@@ -521,6 +521,16 @@
assertEquals(0, MathUtils.nextAfter(-Double.MIN_VALUE, 1), 0);
}
+ public void testScalb() {
+ assertEquals( 0.0, MathUtils.scalb(0.0, 5), 1.0e-15);
+ assertEquals(32.0, MathUtils.scalb(1.0, 5), 1.0e-15);
+ assertEquals(1.0 / 32.0, MathUtils.scalb(1.0, -5), 1.0e-15);
+ assertEquals(Math.PI, MathUtils.scalb(Math.PI, 0), 1.0e-15);
+ assertTrue(Double.isInfinite(MathUtils.scalb(Double.POSITIVE_INFINITY,
1)));
+ assertTrue(Double.isInfinite(MathUtils.scalb(Double.NEGATIVE_INFINITY,
1)));
+ assertTrue(Double.isNaN(MathUtils.scalb(Double.NaN, 1)));
+ }
+
public void testNormalizeAngle() {
for (double a = -15.0; a <= 15.0; a += 0.1) {
for (double b = -15.0; b <= 15.0; b += 0.2) {
