Author: erans
Date: Wed Apr 27 11:54:16 2011
New Revision: 1097088
URL: http://svn.apache.org/viewvc?rev=1097088&view=rev
Log:
MATH-561
Map a value to the interval [O, period).
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java
commons/proper/math/trunk/src/test/java/org/apache/commons/math/util/MathUtilsTest.java
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java?rev=1097088&r1=1097087&r2=1097088&view=diff
==============================================================================
---
commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java
(original)
+++
commons/proper/math/trunk/src/main/java/org/apache/commons/math/util/MathUtils.java
Wed Apr 27 11:54:16 2011
@@ -1281,6 +1281,22 @@ public final class MathUtils {
return a - TWO_PI * FastMath.floor((a + FastMath.PI - center) /
TWO_PI);
}
+ /**
+ * Reduce to the primary interval {@code [0 period)}.
+ *
+ * @param a Value to reduce.
+ * @param period Period.
+ * @param offset Value that will be mapped to {@code 0}.
+ * @return the value, within the interval {@code [0 period)},
+ * that corresponds to {@code a}.
+ */
+ public static double reduce(double a,
+ double period,
+ double offset) {
+ final double p = Math.abs(period);
+ return a - p * Math.floor((a - offset) / p) - offset;
+ }
+
/**
* <p>Normalizes an array to make it sum to a specified value.
* Returns the result of the transformation <pre>
Modified:
commons/proper/math/trunk/src/test/java/org/apache/commons/math/util/MathUtilsTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/util/MathUtilsTest.java?rev=1097088&r1=1097087&r2=1097088&view=diff
==============================================================================
---
commons/proper/math/trunk/src/test/java/org/apache/commons/math/util/MathUtilsTest.java
(original)
+++
commons/proper/math/trunk/src/test/java/org/apache/commons/math/util/MathUtilsTest.java
Wed Apr 27 11:54:16 2011
@@ -1054,6 +1054,55 @@ public final class MathUtilsTest {
}
@Test
+ public void testReduce() {
+ final double period = -12.222;
+ final double offset = 13;
+
+ final double delta = 1.5;
+
+ double orig = offset + 122456789 * period + delta;
+ double expected = delta;
+ Assert.assertEquals(expected,
+ MathUtils.reduce(orig, period, offset),
+ 1e-7);
+ Assert.assertEquals(expected,
+ MathUtils.reduce(orig, -period, offset),
+ 1e-7);
+
+ orig = offset - 123356789 * period - delta;
+ expected = Math.abs(period) - delta;
+ Assert.assertEquals(expected,
+ MathUtils.reduce(orig, period, offset),
+ 1e-6);
+ Assert.assertEquals(expected,
+ MathUtils.reduce(orig, -period, offset),
+ 1e-6);
+
+ orig = offset - 123446789 * period + delta;
+ expected = delta;
+ Assert.assertEquals(expected,
+ MathUtils.reduce(orig, period, offset),
+ 1e-6);
+ Assert.assertEquals(expected,
+ MathUtils.reduce(orig, -period, offset),
+ 1e-6);
+ }
+
+ @Test
+ public void testReduceComparedWithNormalizeAngle() {
+ final double tol = Math.ulp(1d);
+ final double period = 2 * Math.PI;
+ for (double a = -15; a <= 15; a += 0.5) {
+ for (double center = -15; center <= 15; center += 1) {
+ final double nA = MathUtils.normalizeAngle(a, center);
+ final double offset = center - Math.PI;
+ final double r = MathUtils.reduce(a, period, offset);
+ Assert.assertEquals(nA, r + offset, tol);
+ }
+ }
+ }
+
+ @Test
public void testNormalizeArray() {
double[] testValues1 = new double[] {1, 1, 2};
TestUtils.assertEquals(
