Class SloppyMath


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

      • PIO2_HI

        private static final double PIO2_HI
      • PIO2_LO

        private static final double PIO2_LO
      • TWOPI_HI

        private static final double TWOPI_HI
      • TWOPI_LO

        private static final double TWOPI_LO
      • SIN_COS_DELTA_HI

        private static final double SIN_COS_DELTA_HI
      • SIN_COS_DELTA_LO

        private static final double SIN_COS_DELTA_LO
      • SIN_COS_INDEXER

        private static final double SIN_COS_INDEXER
      • sinTab

        private static final double[] sinTab
      • cosTab

        private static final double[] cosTab
      • SIN_COS_MAX_VALUE_FOR_INT_MODULO

        static final double SIN_COS_MAX_VALUE_FOR_INT_MODULO
      • ASIN_MAX_VALUE_FOR_TABS

        private static final double ASIN_MAX_VALUE_FOR_TABS
      • ASIN_DELTA

        private static final double ASIN_DELTA
      • ASIN_INDEXER

        private static final double ASIN_INDEXER
      • asinTab

        private static final double[] asinTab
      • asinDer1DivF1Tab

        private static final double[] asinDer1DivF1Tab
      • asinDer2DivF2Tab

        private static final double[] asinDer2DivF2Tab
      • asinDer3DivF3Tab

        private static final double[] asinDer3DivF3Tab
      • asinDer4DivF4Tab

        private static final double[] asinDer4DivF4Tab
      • ASIN_PIO2_HI

        private static final double ASIN_PIO2_HI
      • ASIN_PIO2_LO

        private static final double ASIN_PIO2_LO
      • ASIN_PS0

        private static final double ASIN_PS0
      • ASIN_PS1

        private static final double ASIN_PS1
      • ASIN_PS2

        private static final double ASIN_PS2
      • ASIN_PS3

        private static final double ASIN_PS3
      • ASIN_PS4

        private static final double ASIN_PS4
      • ASIN_PS5

        private static final double ASIN_PS5
      • ASIN_QS1

        private static final double ASIN_QS1
      • ASIN_QS2

        private static final double ASIN_QS2
      • ASIN_QS3

        private static final double ASIN_QS3
      • ASIN_QS4

        private static final double ASIN_QS4
    • 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.
      • 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)