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new 00f9f4e NUMBERS-157: Reduce to primary interval.
00f9f4e is described below
commit 00f9f4ec702a428ac0e244a424a16e19a8afc71a
Author: Gilles Sadowski <gillese...@gmail.com>
AuthorDate: Wed May 26 16:49:56 2021 +0200
NUMBERS-157: Reduce to primary interval.
Functionality ported from "Commons Math".
---
.../org/apache/commons/numbers/angle/Reduce.java | 49 +++++++++
.../apache/commons/numbers/angle/ReduceTest.java | 110 +++++++++++++++++++++
2 files changed, 159 insertions(+)
diff --git
a/commons-numbers-angle/src/main/java/org/apache/commons/numbers/angle/Reduce.java
b/commons-numbers-angle/src/main/java/org/apache/commons/numbers/angle/Reduce.java
new file mode 100644
index 0000000..7123c2d
--- /dev/null
+++
b/commons-numbers-angle/src/main/java/org/apache/commons/numbers/angle/Reduce.java
@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.numbers.angle;
+
+import java.util.function.DoubleUnaryOperator;
+
+/**
+ * Reduces {@code |a - offset|} to the primary interval {@code [0, |period|)}.
+ *
+ * Specifically, the {@link #applyAsDouble(double) computed value} is:
+ * {@code a - |period| * floor((a - offset) / |period|) - offset}.
+ */
+public class Reduce implements DoubleUnaryOperator {
+ /** Offset. */
+ private final double offset;
+ /** Period. */
+ private final double period;
+
+ /**
+ * @param offset Value that will be mapped to {@code 0}.
+ * @param period Period.
+ */
+ public Reduce(double offset,
+ double period) {
+ this.offset = offset;
+ this.period = Math.abs(period);
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public double applyAsDouble(double x) {
+ final double xMo = x - offset;
+ return xMo - period * Math.floor(xMo / period);
+ }
+}
diff --git
a/commons-numbers-angle/src/test/java/org/apache/commons/numbers/angle/ReduceTest.java
b/commons-numbers-angle/src/test/java/org/apache/commons/numbers/angle/ReduceTest.java
new file mode 100644
index 0000000..f78818f
--- /dev/null
+++
b/commons-numbers-angle/src/test/java/org/apache/commons/numbers/angle/ReduceTest.java
@@ -0,0 +1,110 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.numbers.angle;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test cases for the {@link Reduce} class.
+ */
+class ReduceTest {
+ @Test
+ void testReduce() {
+ final double period = 12.222;
+ final double offset = 13456.789;
+
+ final double delta = 1.5;
+
+ double orig = offset + 122456789 * period + delta;
+ double expected = delta;
+
+ final Reduce r = new Reduce(offset, period);
+ Assertions.assertEquals(expected,
+ r.applyAsDouble(orig),
+ 1e-7);
+
+ orig = offset - 123356789 * period - delta;
+ expected = Math.abs(period) - delta;
+ Assertions.assertEquals(expected,
+ r.applyAsDouble(orig),
+ 1e-6);
+
+ orig = offset - 123446789 * period + delta;
+ expected = delta;
+ Assertions.assertEquals(expected,
+ r.applyAsDouble(orig),
+ 1e-6);
+ }
+
+ @Test
+ void testNaN() {
+ final double[] values = new double[] {
+ 12.345, -9876.5, Double.NaN, Double.POSITIVE_INFINITY,
Double.NEGATIVE_INFINITY
+ };
+
+ for (double offset : values) {
+ for (double period : values) {
+ for (double x : values) {
+ final boolean expectedNaN = Double.isNaN(x) ||
Double.isInfinite(x) ||
+ Double.isNaN(period) || Double.isInfinite(period) ||
+ Double.isNaN(offset) || Double.isInfinite(offset);
+
+ final double v = new Reduce(offset,
period).applyAsDouble(x);
+ if (expectedNaN) {
+ Assertions.assertTrue(Double.isNaN(v));
+ } else {
+ Assertions.assertFalse(Double.isNaN(v));
+ }
+ }
+ }
+ }
+ }
+
+ @Test
+ void testReduceNegativePeriod() {
+ final double period = 12.222;
+ final double offset = 13;
+ final double delta = 1.5;
+ double orig = offset + 122456789 * period + delta;
+ double expected = delta;
+
+ final Reduce r1 = new Reduce(offset, period);
+ final Reduce r2 = new Reduce(offset, -period);
+ Assertions.assertEquals(expected,
+ r1.applyAsDouble(orig),
+ 1e-7);
+ Assertions.assertEquals(r1.applyAsDouble(orig),
+ r2.applyAsDouble(orig),
+ 0d);
+ }
+
+ @Test
+ void testReduceComparedWithNormalize() {
+ 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 = PlaneAngleRadians.normalize(a, center);
+ final double offset = center - Math.PI;
+ final Reduce reduce = new Reduce(offset, period);
+ final double r = reduce.applyAsDouble(a) + offset;
+ Assertions.assertEquals(nA, r, 52 * Math.ulp(nA),
+ "a=" + a + " center=" + center);
+ }
+ }
+ }
+}
