math.geom2d
Class Vector2D

java.lang.Object
  math.geom2d.Vector2D

All Implemented Interfaces:

java.lang.Cloneable, GeometricObject2D

public class Vector2D
extends java.lang.Object
implements GeometricObject2D, java.lang.Cloneable

A vector in the 2D plane. Provides methods to compute cross product and dot product, addition and subtraction of vectors.

Constructor Summary

Vector2D()
Constructs a new Vectors initialized with x=1 and y=0.

Vector2D(double x, double y)
Constructs a new vector with the given coordinates.

Vector2D(Point2D point)
Constructs a new vector between the origin and the given point.

Vector2D(Point2D point1, Point2D point2)
Constructs a new vector between two points

Method Summary

boolean	almostEquals(GeometricObject2D obj, double eps) Test whether this object is the same as another vector, with respect to a given threshold.
double	angle() Returns the angle with the horizontal axis, in radians.
Vector2D	clone()
static Vector2D	create(double x, double y) Deprecated. since 0.11.1
static Vector2D	create(Point2D point) Deprecated. since 0.11.1
static Vector2D	createPolar(double rho, double theta) Creates a new vector by specifying the distance to the origin, and the angle with the horizontal.
double	cross(Vector2D v) Get the cross product with point p.
static double	cross(Vector2D v1, Vector2D v2) Get the cross product of the two vectors, defined by : dx1*dy2 - dx2*dy1 Cross product is zero for colinear vectors.
double	dot(Vector2D v) Get the dot product with point p.
static double	dot(Vector2D v1, Vector2D v2) Get the dot product of the two vectors, defined by : dx1*dy2 + dx2*dy1 Dot product is zero if the vectors defined by the 2 vectors are orthogonal.
boolean	equals(java.lang.Object obj) Test whether this object is exactly the same as another vector.
double	getX() Deprecated. replaces by x() (since 0.11.1)
double	getY() Deprecated. replaces by y() (since 0.11.1)
boolean	isColinear(Vector2D v) test if the two vectors are colinear
static boolean	isColinear(Vector2D v1, Vector2D v2) Tests if the two vectors are colinear
boolean	isOrthogonal(Vector2D v) test if the two vectors are orthogonal
static boolean	isOrthogonal(Vector2D v1, Vector2D v2) Tests if the two vectors are orthogonal
Vector2D	minus(Vector2D v) Returns the subtraction of current vector with vector given as parameter.
double	norm() Computes the norm of the vector
Vector2D	normalize() Returns the vector with same direction as this one, but with norm equal to 1.
Vector2D	opposite() Returns the opposite vector v2 of this, such that the sum of this and v2 equals the null vector.
Vector2D	plus(Vector2D v) Returns the sum of current vector with vector given as parameter.
Vector2D	rotate(double theta) Rotates the vector by the given angle.
Vector2D	times(double k) Multiplies the vector by a scalar amount.
java.lang.String	toString() Display the coordinates of the vector.
Vector2D	transform(AffineTransform2D trans) Transform the vector, by using only the first 4 parameters of the transform.
double	x() Returns the x coordinates of this vector.
double	y() Returns the y coordinates of this vector.

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Vector2D

public Vector2D()

Constructs a new Vectors initialized with x=1 and y=0.

Vector2D

public Vector2D(double x,
                double y)

Constructs a new vector with the given coordinates. Consider creating a new Vector using static factory.

Vector2D

public Vector2D(Point2D point)

Constructs a new vector between the origin and the given point.

Vector2D

public Vector2D(Point2D point1,
                Point2D point2)

Constructs a new vector between two points

Method Detail

create

@Deprecated
public static Vector2D create(double x,
                                         double y)

Deprecated. since 0.11.1

Static factory for creating a new vector in Cartesian coordinates.

create

@Deprecated
public static Vector2D create(Point2D point)

Deprecated. since 0.11.1

Static factory for creating a new vector from the coordinate of a point.

createPolar

public static Vector2D createPolar(double rho,
                                   double theta)

Creates a new vector by specifying the distance to the origin, and the angle with the horizontal.

dot

public static double dot(Vector2D v1,
                         Vector2D v2)

Get the dot product of the two vectors, defined by :

dx1*dy2 + dx2*dy1

Dot product is zero if the vectors defined by the 2 vectors are orthogonal. It is positive if vectors are in the same direction, and negative if they are in opposite direction.

cross

public static double cross(Vector2D v1,
                           Vector2D v2)

Get the cross product of the two vectors, defined by :

dx1*dy2 - dx2*dy1

Cross product is zero for colinear vectors. It is positive if angle between vector 1 and vector 2 is comprised between 0 and PI, and negative otherwise.

isColinear

public static boolean isColinear(Vector2D v1,
                                 Vector2D v2)

Tests if the two vectors are colinear

Returns:

true if the vectors are colinear

isOrthogonal

public static boolean isOrthogonal(Vector2D v1,
                                   Vector2D v2)

Tests if the two vectors are orthogonal

Returns:

true if the vectors are orthogonal

x

public double x()

Returns the x coordinates of this vector.

getX

@Deprecated
public double getX()

Deprecated. replaces by x() (since 0.11.1)

y

public double y()

Returns the y coordinates of this vector.

getY

@Deprecated
public double getY()

Deprecated. replaces by y() (since 0.11.1)

opposite

public Vector2D opposite()

Returns the opposite vector v2 of this, such that the sum of this and v2 equals the null vector.

Returns:

the vector opposite to this.

norm

public double norm()

Computes the norm of the vector

Returns:

the euclidean norm of the vector

angle

public double angle()

Returns the angle with the horizontal axis, in radians.

Returns:

the horizontal angle of the vector

normalize

public Vector2D normalize()

Returns the vector with same direction as this one, but with norm equal to 1.

isColinear

public boolean isColinear(Vector2D v)

test if the two vectors are colinear

Returns:

true if the vectors are colinear

isOrthogonal

public boolean isOrthogonal(Vector2D v)

test if the two vectors are orthogonal

Returns:

true if the vectors are orthogonal

dot

public double dot(Vector2D v)

Get the dot product with point p. Dot product id defined by:

x1*y2 + x2*y1

. Dot product is zero if the vectors defined by the 2 points are orthogonal. It is positive if vectors are in the same direction, and negative if they are in opposite direction.

cross

public double cross(Vector2D v)

Get the cross product with point p. Cross product is defined by :

x1*y2 - x2*y1

. Cross product is zero for colinear vector. It is positive if angle between vector 1 and vector 2 is comprised between 0 and PI, and negative otherwise.

plus

public Vector2D plus(Vector2D v)

Returns the sum of current vector with vector given as parameter. Inner fields are not modified.

minus

public Vector2D minus(Vector2D v)

Returns the subtraction of current vector with vector given as parameter. Inner fields are not modified.

times

public Vector2D times(double k)

Multiplies the vector by a scalar amount. Inner fields are not

Parameters:

k - the scale factor

Returns:

the scaled vector

Since:

0.7.0

rotate

public Vector2D rotate(double theta)

Rotates the vector by the given angle.

Parameters:

theta - the angle of rotation, in radians counter-clockwise

transform

public Vector2D transform(AffineTransform2D trans)

Transform the vector, by using only the first 4 parameters of the transform. Translation of a vector returns the same vector.

Parameters:

trans - an affine transform

Returns:

the transformed vector.

almostEquals

public boolean almostEquals(GeometricObject2D obj,
                            double eps)

Test whether this object is the same as another vector, with respect to a given threshold.

Specified by:

almostEquals in interface GeometricObject2D

Parameters:

obj - the object to compare

eps - a threshold value, for example the minimal coordinate difference

Returns:

true if both object have the same value up to the threshold

equals

public boolean equals(java.lang.Object obj)

Test whether this object is exactly the same as another vector.

Overrides:

equals in class java.lang.Object

See Also:

almostEquals(math.geom2d.GeometricObject2D, double)

toString

public java.lang.String toString()

Display the coordinates of the vector. Typical output is: x=3 y=4.

Overrides:

toString in class java.lang.Object

clone

public Vector2D clone()

Overrides:

clone in class java.lang.Object