Class SloppyMath


  • public class SloppyMath
    extends Object
    Math functions that trade off accuracy for speed.
    • Constructor Detail

      • SloppyMath

        public SloppyMath()
    • Method Detail

      • haversinMeters

        public static double haversinMeters​(double lat1,
                                            double lon1,
                                            double lat2,
                                            double lon2)
        Returns the Haversine distance in meters between two points specified in decimal degrees (latitude/longitude). This works correctly even if the dateline is between the two points.

        Error is at most 4E-1 (40cm) from the actual haversine distance, but is typically much smaller for reasonable distances: around 1E-5 (0.01mm) for distances less than 1000km.

        Parameters:
        lat1 - Latitude of the first point.
        lon1 - Longitude of the first point.
        lat2 - Latitude of the second point.
        lon2 - Longitude of the second point.
        Returns:
        distance in meters.
      • haversinMeters

        public static double haversinMeters​(double sortKey)
        Returns the Haversine distance in meters between two points given the previous result from haversinSortKey(double, double, double, double)
        Returns:
        distance in meters.
      • haversinKilometers

        @Deprecated
        public static double haversinKilometers​(double lat1,
                                                double lon1,
                                                double lat2,
                                                double lon2)
        Deprecated.
        Returns the Haversine distance in kilometers between two points specified in decimal degrees (latitude/longitude). This works correctly even if the dateline is between the two points.
        Parameters:
        lat1 - Latitude of the first point.
        lon1 - Longitude of the first point.
        lat2 - Latitude of the second point.
        lon2 - Longitude of the second point.
        Returns:
        distance in kilometers.
      • haversinSortKey

        public static double haversinSortKey​(double lat1,
                                             double lon1,
                                             double lat2,
                                             double lon2)
        Returns a sort key for distance. This is less expensive to compute than haversinMeters(double, double, double, double), but it always compares the same. This can be converted into an actual distance with haversinMeters(double), which effectively does the second half of the computation.
      • cos

        public static double cos​(double a)
        Returns the trigonometric cosine of an angle.

        Error is around 1E-15.

        Special cases:

        • If the argument is NaN or an infinity, then the result is NaN.
        Parameters:
        a - an angle, in radians.
        Returns:
        the cosine of the argument.
        See Also:
        Math.cos(double)
      • asin

        public static double asin​(double a)
        Returns the arc sine of a value.

        The returned angle is in the range -pi/2 through pi/2. Error is around 1E-7.

        Special cases:

        • If the argument is NaN or its absolute value is greater than 1, then the result is NaN.
        Parameters:
        a - the value whose arc sine is to be returned.
        Returns:
        arc sine of the argument
        See Also:
        Math.asin(double)
      • toDegrees

        public static double toDegrees​(double radians)
        Convert to degrees.
        Parameters:
        radians - radians to convert to degrees
        Returns:
        degrees
      • toRadians

        public static double toRadians​(double degrees)
        Convert to radians.
        Parameters:
        degrees - degrees to convert to radians
        Returns:
        radians