/**
  This file is created by Yu Dong (2023).
  License  : Apache 2.0
  FileName : Math.cj
  Author   : Yu Dong
  Version  : 0.0.1
  Date     : 20230424
  Note     : First Commit
 */

/**
 * @file
 * Math
 */
package gistools.base

import std.math.*


// base parameter
let x_PI = Float64.PI * 3000.0 / 180.0

// 地球椭球体 - 长半轴
let a = 6378245.0
// 地球椭球体 - 扁率
let ee = 0.00669342162296594323

// 地球赤道周长的一半 墨卡托坐标x轴区间[-20037508.3427892,20037508.3427892]
let halfRadius = 20037508.34

// 地球半径（米）
let earthRadiusMeters : Float64 = 6371006.0

// 米每度
let metersPerDegree : Float64 = 2.0 * Float64.PI * earthRadiusMeters / 360.0

// 弧度每度
let radiansPerDegree : Float64 = Float64.PI / 180.0

// 度每弧度
let degreesPerRadian : Float64 = 180.0 / Float64.PI


/**
  * The Function is to compute atan2 with 2 values
  *
  * @param x of Float64
  * @param y of Float64
  *
  * @return Type of Float64
  * @since 0.38.2
  */
public func atan2(x : Float64, y : Float64): Float64 {
    if (y < 0.0 && x < 0.0) {
        atan(y/x) - Float64.PI
    } else if (y > 0.0 && x < 0.0) {
        atan(y/x) + Float64.PI
    } else {
        atan(y/x)
    }        
}


/**
 * Ordered Pair
 *
 * @author Yu Dong
 * @since 0.38.2
 */
public interface OrderedPair {
    
    mut prop x : Float64
    
    mut prop y : Float64
}