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MATH-904. 

Fixed wrong assumption in "pow" method.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1413916 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Gilles Sadowski 2012-11-26 23:02:29 +00:00
parent 4673043763
commit 6844aba987
3 changed files with 16 additions and 1 deletions
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3
src/changes/changes.xml
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@ -52,6 +52,9 @@ If the output is not quite correct, check for invisible trailing spaces!
<body>
<release version="3.1" date="TBD" description="
">
<action dev="erans" type="fix" issue="MATH-904" due-to="Jeff Hain">
Fixed "pow" method in class "FastMath".
</action>
<action dev="erans" type="update" issue="MATH-902" due-to="Bruce A. Johnson">
Created a "maximum number of iterations" stopping criterion in the
convergence checkers (package "o.a.c.m.optimization") that allows the

4
src/main/java/org/apache/commons/math3/util/FastMath.java
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@ -309,6 +309,8 @@ public class FastMath {
/** 2^52 - double numbers this large must be integral (no fraction) or NaN or Infinite */
private static final double TWO_POWER_52 = 4503599627370496.0;
/** 2^53 - double numbers this large must be even. */
private static final double TWO_POWER_53 = 2 * TWO_POWER_52;
/** Constant: {@value}. */
private static final double F_1_3 = 1d / 3d;
@ -1537,7 +1539,7 @@ public class FastMath {
/* Handle special case x<0 */
if (x < 0) {
// y is an even integer in this case
if (y >= TWO_POWER_52 || y <= -TWO_POWER_52) {
if (y >= TWO_POWER_53 || y <= -TWO_POWER_53) {
return pow(-x, y);
}

10
src/test/java/org/apache/commons/math3/util/FastMathTest.java
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@ -157,6 +157,16 @@ public class FastMathTest {
}
@Test
public void testMath904() {
final double x = -1;
final double y = (5 + 1e-15) * 1e15;
Assert.assertEquals(Math.pow(x, y),
FastMath.pow(x, y), 0);
Assert.assertEquals(Math.pow(x, -y),
FastMath.pow(x, -y), 0);
}
@Test
public void testMath905LargePositive() {
final double start = StrictMath.log(Double.MAX_VALUE);