org.bukkit.craftbukkit.TrigMath Maven / Gradle / Ivy

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A spigot fork to kotlin structure and news.

There is a newer version: 2.4.0

package org.bukkit.craftbukkit;

/**
 * Credits for this class goes to user aioobe on stackoverflow.com
 * Source: http://stackoverflow.com/questions/4454630/j2me-calculate-the-the-distance-between-2-latitude-and-longitude
 */
public class TrigMath {

  static final double sq2p1 = 2.414213562373095048802e0;
  static final double sq2m1 = .414213562373095048802e0;
  static final double p4 = .161536412982230228262e2;
  static final double p3 = .26842548195503973794141e3;
  static final double p2 = .11530293515404850115428136e4;
  static final double p1 = .178040631643319697105464587e4;
  static final double p0 = .89678597403663861959987488e3;
  static final double q4 = .5895697050844462222791e2;
  static final double q3 = .536265374031215315104235e3;
  static final double q2 = .16667838148816337184521798e4;
  static final double q1 = .207933497444540981287275926e4;
  static final double q0 = .89678597403663861962481162e3;
  static final double PIO2 = 1.5707963267948966135E0;

  private static double mxatan(double arg) {
    double argsq = arg * arg, value;

    value = ((((p4 * argsq + p3) * argsq + p2) * argsq + p1) * argsq + p0);
    value = value / (((((argsq + q4) * argsq + q3) * argsq + q2) * argsq + q1) * argsq + q0);
    return value * arg;
  }

  private static double msatan(double arg) {
    return arg < sq2m1 ? mxatan(arg)
      : arg > sq2p1 ? PIO2 - mxatan(1 / arg)
      : PIO2 / 2 + mxatan((arg - 1) / (arg + 1));
  }

  public static double atan(double arg) {
    return arg > 0 ? msatan(arg) : -msatan(-arg);
  }

  public static double atan2(double arg1, double arg2) {
    if (arg1 + arg2 == arg1)
      return arg1 >= 0 ? PIO2 : -PIO2;
    arg1 = atan(arg1 / arg2);
    return arg2 < 0 ? arg1 <= 0 ? arg1 + Math.PI : arg1 - Math.PI : arg1;
  }
}