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The Apache Commons Math project is a library of lightweight, self-contained mathematics and statistics components addressing the most common practical problems not immediately available in the Java programming language or commons-lang.
/*
* 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.math3.geometry.spherical.oned;
import org.apache.commons.math3.exception.NumberIsTooLargeException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.geometry.partitioning.Region.Location;
import org.apache.commons.math3.util.FastMath;
import org.apache.commons.math3.util.MathUtils;
import org.apache.commons.math3.util.Precision;
/** This class represents an arc on a circle.
* @see ArcsSet
* @since 3.3
*/
public class Arc {
/** The lower angular bound of the arc. */
private final double lower;
/** The upper angular bound of the arc. */
private final double upper;
/** Middle point of the arc. */
private final double middle;
/** Tolerance below which angles are considered identical. */
private final double tolerance;
/** Simple constructor.
*
* If either {@code lower} is equals to {@code upper} or
* the interval exceeds \( 2 \pi \), the arc is considered
* to be the full circle and its initial defining boundaries
* will be forgotten. {@code lower} is not allowed to be
* greater than {@code upper} (an exception is thrown in this case).
* {@code lower} will be canonicalized between 0 and \( 2 \pi \), and
* upper shifted accordingly, so the {@link #getInf()} and {@link #getSup()}
* may not return the value used at instance construction.
*
* @param lower lower angular bound of the arc
* @param upper upper angular bound of the arc
* @param tolerance tolerance below which angles are considered identical
* @exception NumberIsTooLargeException if lower is greater than upper
*/
public Arc(final double lower, final double upper, final double tolerance)
throws NumberIsTooLargeException {
this.tolerance = tolerance;
if (Precision.equals(lower, upper, 0) || (upper - lower) >= MathUtils.TWO_PI) {
// the arc must cover the whole circle
this.lower = 0;
this.upper = MathUtils.TWO_PI;
this.middle = FastMath.PI;
} else if (lower <= upper) {
this.lower = MathUtils.normalizeAngle(lower, FastMath.PI);
this.upper = this.lower + (upper - lower);
this.middle = 0.5 * (this.lower + this.upper);
} else {
throw new NumberIsTooLargeException(LocalizedFormats.ENDPOINTS_NOT_AN_INTERVAL,
lower, upper, true);
}
}
/** Get the lower angular bound of the arc.
* @return lower angular bound of the arc,
* always between 0 and \( 2 \pi \)
*/
public double getInf() {
return lower;
}
/** Get the upper angular bound of the arc.
* @return upper angular bound of the arc,
* always between {@link #getInf()} and {@link #getInf()} \( + 2 \pi \)
*/
public double getSup() {
return upper;
}
/** Get the angular size of the arc.
* @return angular size of the arc
*/
public double getSize() {
return upper - lower;
}
/** Get the barycenter of the arc.
* @return barycenter of the arc
*/
public double getBarycenter() {
return middle;
}
/** Get the tolerance below which angles are considered identical.
* @return tolerance below which angles are considered identical
*/
public double getTolerance() {
return tolerance;
}
/** Check a point with respect to the arc.
* @param point point to check
* @return a code representing the point status: either {@link
* Location#INSIDE}, {@link Location#OUTSIDE} or {@link Location#BOUNDARY}
*/
public Location checkPoint(final double point) {
final double normalizedPoint = MathUtils.normalizeAngle(point, middle);
if (normalizedPoint < lower - tolerance || normalizedPoint > upper + tolerance) {
return Location.OUTSIDE;
} else if (normalizedPoint > lower + tolerance && normalizedPoint < upper - tolerance) {
return Location.INSIDE;
} else {
return (getSize() >= MathUtils.TWO_PI - tolerance) ? Location.INSIDE : Location.BOUNDARY;
}
}
}