inra.ijpb.geometry

Class Vector2D

java.lang.Object

inra.ijpb.geometry.Vector2D

public class Vector2D
extends Object

Represents a couple of coordinates in linear space, and provides some computing methods. The class is immutable.

Author:

dlegland

Constructor Summary

Constructors

Constructor and Description
Vector2D() Empty constructor, with all coordinates initialized to zero.
Vector2D(double x, double y) Initialization constructor.

Method Summary

Modifier and Type	Method and Description
boolean	almostEquals(Vector2D v, double eps) Checks if this vector is close to the given vector, by checking each coordinate using the given threshold.
static double	angle(Vector2D v1, Vector2D v2) Computes the angle between two vectors.
static double	crossProduct(Vector2D v1, Vector2D v2) Computes the cross product of the two vectors.
static double	dotProduct(Vector2D v1, Vector2D v2) Computes the dot product of two vectors, defined by:
double	getNorm() Computes the norm of the vector, given as the square root of the sum of squared coordinates.
double	getX() Returns the x coordinate of the vector.
double	getY() Returns the y coordinate of the vector.
Vector2D	minus(Vector2D v) Returns the result of the subtraction of this vector with another vector.
Vector2D	normalize() Returns a normalized vector with same direction as this vector
Vector2D	plus(Vector2D v) Returns the result of the addition of this vector with another vector.
Vector2D	times(double k) Returns the result of the multiplication of this vector with a scalar value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Vector2D

public Vector2D()

Empty constructor, with all coordinates initialized to zero.

Vector2D

public Vector2D(double x,
                double y)

Initialization constructor.

Parameters:

x - the x coordinate

y - the y coordinate

Method Detail

crossProduct

public static final double crossProduct(Vector2D v1,
                                        Vector2D v2)

Computes the cross product of the two vectors. Cross product is zero for colinear vectors.

Parameters:

v1 - the first vector

v2 - the second vector

Returns:

the cross product of the two vectors

dotProduct

public static final double dotProduct(Vector2D v1,
                                      Vector2D v2)

Computes the dot product of two vectors, defined by:

x1 * x2 + y1 * y2

Dot product is zero if the vectors are orthogonal. It is positive if vectors are in the same direction, and negative if they are in opposite direction.

Parameters:

v1 - the first vector

v2 - the second vector

Returns:

the dot product of the two vectors

angle

public static final double angle(Vector2D v1,
                                 Vector2D v2)

Computes the angle between two vectors. Result is given in radians.

Parameters:

v1 - the first vector

v2 - the second vector

Returns:

the angle between the two vectors, in radians

getX

public double getX()

Returns the x coordinate of the vector.

Returns:

the x coordinate of the vector

getY

public double getY()

Returns the y coordinate of the vector.

Returns:

the y coordinate of the vector

plus

public Vector2D plus(Vector2D v)

Returns the result of the addition of this vector with another vector.

Parameters:

v - the vector to add

Returns:

the results of the vector addition

minus

public Vector2D minus(Vector2D v)

Returns the result of the subtraction of this vector with another vector.

Parameters:

v - the vector to subtract

Returns:

the results of the vector subtraction

times

public Vector2D times(double k)

Returns the result of the multiplication of this vector with a scalar value.

Parameters:

k - the scalar coefficient

Returns:

the results of scalar multiplication

normalize

public Vector2D normalize()

Returns a normalized vector with same direction as this vector

Returns:

the normalized vector with same direction as this.

getNorm

public double getNorm()

Computes the norm of the vector, given as the square root of the sum of squared coordinates.

Returns:

the norm of the vector

almostEquals

public boolean almostEquals(Vector2D v,
                            double eps)

Checks if this vector is close to the given vector, by checking each coordinate using the given threshold.

Parameters:

v - the vector to compare to

eps - the absolute tolerance for comparing coordinates

Returns:

true if vector have same coordinates with respect to tolerance