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Comprehensive Java common library (Java7+)
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/*
 * Copyright (C) 2015-2018 S.Violet
 *
 * Licensed 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.
 *
 * Project GitHub: https://github.com/shepherdviolet/thistle
 * Email: [email protected]
 */

package sviolet.thistle.util.math;

/**
 * 数学工具
 *
 * @author S.Violet
 */
public class MathUtils {

	/*********************************************************************
	 * trigonometric
	 */

	/**
	 * 
	 *	根据角度计算sin值 

	 *	Math.sin()中的参数为弧度值, 弧度值 = 角度 * PI / 180 

	 * 
	 * 
	 * @param angle [0, 360]
	 * @return sin值 [-1, 1]
	 */
	public static double sinAngle(double angle){
		return Math.sin(angle * Math.PI / 180);
	}

	/**
	 * 
	 *	根据sin值计算角度 

	 *	Math.asin()返回值为弧度值, 弧度值 = 角度 * PI / 180 

	 * 
	 *
	 * @param sin sin值 [-1, 1]
	 * @return 角度 [0, 360]
     */
	public static double asinAngle(double sin){
		return Math.asin(sin) / (Math.PI / 180);
	}

	/**
	 * 
	 *	根据角度计算tan值 

	 *	Math.tan()中的参数为弧度值, 弧度值 = 角度 * PI / 180 

	 * 
	 *
	 * @param angle [0, 360]
	 * @return tan值
     */
	public static double tanAngle(double angle){
		return Math.tan(angle * Math.PI / 180);
	}

	/**
	 * 
	 *	根据tan值计算角度 

	 *	Math.atan()返回值为弧度值, 弧度值 = 角度 * PI / 180 

	 * 
	 *
	 * @param tan tan值
	 * @return 角度 [0, 360]
     */
	public static double atanAngle(double tan){
		return Math.atan(tan) / (Math.PI / 180);
	}

	/************************************************************************************
	 * other
     */

	/**
	 * 角度转为弧度(rad)
     */
	public static double rad(double degrees) {
		return degrees * Math.PI / 180.0;
	}

	/**
	 * 角度标准化, 将任意不在0-360范围内的角度转换为0-360范围内的角度, 例如:-90 -> 270
	 * @param angle 角度
	 * @return 0-360范围的角度
     */
	public static float standardizeAngle(float angle){
		float m = angle % 360;
		return m > 0 ? m : m + 360;
	}

	/**
	 * 判断数字是否为2的幂次, 例如1 2 4 8 16 ... 512 1024 ... (0 返回 false)
	 * @param value 数字
	 * @return true:为2的幂次
	 */
	public static boolean isPowerOfTwo(int value){
		return value > 0 && (value & value - 1) == 0;
	}

}