# Normalizes an angle to be near an absolute angle : Math « Development Class « Java

Normalizes an angle to be near an absolute angle

```
/*******************************************************************************
* Copyright (c) 2001, 2008 Mathew A. Nelson and Robocode contributors
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
*
* Contributors:
*     Mathew A. Nelson
*     - Initial API and implementation
*     Flemming N. Larsen
*     - Moved all methods to classes like FileUtil, StringUtil, WindowUtil,
*       Logger etc. exception for the following methods, which have been kept
*       here as legacy robots make use of these methods:
*       - normalAbsoluteAngle()
*       - normalNearAbsoluteAngle()
*       - normalRelativeAngle()
*     - The isNear() was made public
*     - Optimized and provided javadocs for all methods
*******************************************************************************/

import static java.lang.Math.PI;
import java.util.Random;

/**
* Utility class that provide methods for normalizing angles.
*
* @author Mathew A. Nelson (original)
* @author Flemming N. Larsen (contributor)
*/

public class Utils {
private final static double TWO_PI = 2 * PI;
private final static double THREE_PI_OVER_TWO = 3 * PI / 2;
private final static double PI_OVER_TWO = PI / 2;
public static final double NEAR_DELTA = .00001;
/**
* Normalizes an angle to be near an absolute angle.
* The normalized angle will be in the range from 0 to 2*PI, where 2*PI
* itself is not included.
* If the normalized angle is near to 0, PI/2, PI, 3*PI/2 or 2*PI, that
* angle will be returned. The {@link #isNear(double, double) isNear}
* method is used for defining when the angle is near one of angles listed
* above.
*
* @param angle the angle to normalize
* @return the normalized angle that will be in the range of [0,2*PI[
* @see #normalAbsoluteAngle(double)
* @see #isNear(double, double)
*/
public static double normalNearAbsoluteAngle(double angle) {
angle = (angle %= TWO_PI) >= 0 ? angle : (angle + TWO_PI);

if (isNear(angle, PI)) {
return PI;
} else if (angle < PI) {
if (isNear(angle, 0)) {
return 0;
} else if (isNear(angle, PI_OVER_TWO)) {
return PI_OVER_TWO;
}
} else {
if (isNear(angle, THREE_PI_OVER_TWO)) {
return THREE_PI_OVER_TWO;
} else if (isNear(angle, TWO_PI)) {
return 0;
}
}
return angle;
}
/**
* Tests if the two {@code double} values are near to each other.
* It is recommended to use this method instead of testing if the two
* doubles are equal using an this expression: {@code value1 == value2}.
* The reason being, that this expression might never become
* {@code true} due to the precision of double values.
* Whether or not the specified doubles are near to each other is defined by
* the following expression:
* {@code (Math.abs(value1 - value2) < .00001)}
*
* @param value1 the first double value
* @param value2 the second double value
* @return {@code true} if the two doubles are near to each other;
*         {@code false} otherwise.
*/
public static boolean isNear(double value1, double value2) {
return (Math.abs(value1 - value2) < NEAR_DELTA);
}
}

```

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