Package org.apache.lucene.util
Class SloppyMath
java.lang.Object
org.apache.lucene.util.SloppyMath
Math functions that trade off accuracy for speed.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final int
private static final double[]
private static final double[]
private static final double[]
private static final double[]
private static final double[]
private static final double[]
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
private static final double
(package private) static final double
private static final int
private static final double[]
private static final double
private static final double
private static final double
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic double
asin
(double a) Returns the arc sine of a value.static double
cos
(double a) Returns the trigonometric cosine of an angle.static double
haversinMeters
(double sortKey) Returns the Haversine distance in meters between two points given the previous result fromhaversinSortKey(double, double, double, double)
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).static double
haversinSortKey
(double lat1, double lon1, double lat2, double lon2) Returns a sort key for distance.
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Field Details
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TO_METERS
private static final double TO_METERS- See Also:
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ONE_DIV_F2
private static final double ONE_DIV_F2- See Also:
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ONE_DIV_F3
private static final double ONE_DIV_F3- See Also:
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ONE_DIV_F4
private static final double ONE_DIV_F4- See Also:
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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_TABS_SIZE
private static final int SIN_COS_TABS_SIZE- See Also:
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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_TABS_SIZE
private static final int ASIN_TABS_SIZE- See Also:
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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
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Constructor Details
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SloppyMath
public SloppyMath()
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Method Details
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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.
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haversinMeters
public static double haversinMeters(double sortKey) Returns the Haversine distance in meters between two points given the previous result fromhaversinSortKey(double, double, double, double)
- Returns:
- distance in meters.
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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 thanhaversinMeters(double, double, double, double)
, but it always compares the same. This can be converted into an actual distance withhaversinMeters(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 isNaN
.
- Parameters:
a
- an angle, in radians.- Returns:
- the cosine of the argument.
- See Also:
- If the argument is
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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 isNaN
.
- Parameters:
a
- the value whose arc sine is to be returned.- Returns:
- arc sine of the argument
- See Also:
- If the argument is
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