ch.aplu.android.ev3

Class Vector2D

java.lang.Object

ch.aplu.android.ev3.Vector2D

public class Vector2D
extends java.lang.Object

Class representing a two-dimensional vector with double coordinates (x, y). The following situation is assumed:

     (0, 0) o------------------>x-axis
            | .  / direction
            |  .
            |   .vector
            |    .
            |     .
            |      *
            v
          y-axis

 

The direction of the vector is defined as the angle (0..2*pi) of the vector direction clockwise with reference to the x-coordinate direction.

Field Summary

Fields

Modifier and Type	Field and Description
double	x The public x-coordinate.
double	y The public y-coordinate.

Constructor Summary

Constructors

Constructor and Description
Vector2D() Constructs a zero vector (with coordinates (0, 0)).
Vector2D(double x, double y) Constructs a vector from given double x-y-coordinates.
Vector2D(float x, float y) Constructs a vector from given float x-y-coordinates.
Vector2D(int x, int y) Constructs a vector from given integer x-y-coordinates.

Method Summary

Methods

Modifier and Type	Method and Description
Vector2D	add(Vector2D v) Returns a new vector that is the vector sum of the current vector and the given vector.
Vector2D	clone() Returns a new vector with the same coordinates as the current vector.
double	distanceTo(Vector2D v) Returns the distance between the current vector and the given vector.
double	dot(Vector2D v) Returns the scalar product (dot product) of the current vector with the given vector.
double	getDirection() Returns the direction of the vector (range 0..2*pi)
Vector2D	getNormalized() Returns a new vector with magnitude 1 in the direction of the given vector.
Vector2D	invert() Returns a new vector with inverted coordinates.
boolean	isEqual(Vector2D v) Returns true, if the current vector is identical to the given vector.
double	magnitude() Returns the magnitude (length) of the vector.
double	magnitude2() Returns the square of the magnitude, without squareroot calculation.
Vector2D	mult(double b) Returns a new vector that is the product by a scalar of the current vector and the given double.
Vector2D	mult(float b) Returns a new vector that is the product by a scalar of the current vector and the given float.
Vector2D	mult(int b) Returns a new vector that is the product by a scalar of the current vector and the given integer.
void	normalize() Modifies the vector to unit magnitude.
void	rotate(double angle) Rotates the vector by the specified angle.
Vector2D	sub(Vector2D v) Returns a new vector that is the vector difference of the current vector and the given vector.
java.lang.String	toString() Returns a string with the x-y-coordinates in the format (x,y).

Methods inherited from class java.lang.Object

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

Field Detail

x

public double x

The public x-coordinate.

y

public double y

The public y-coordinate.

Constructor Detail

Vector2D

public Vector2D()

Constructs a zero vector (with coordinates (0, 0)).

Vector2D

public Vector2D(int x,
        int y)

Constructs a vector from given integer x-y-coordinates.

Parameters:

x - the x-coordinate of the vector

y - the y-coordinate of the vector

Vector2D

public Vector2D(float x,
        float y)

Constructs a vector from given float x-y-coordinates.

Parameters:

x - the x-coordinate of the vector

y - the y-coordinate of the vector

Vector2D

public Vector2D(double x,
        double y)

Constructs a vector from given double x-y-coordinates.

Parameters:

x - the x-coordinate of the vector

y - the y-coordinate of the vector

Method Detail

magnitude

public double magnitude()

Returns the magnitude (length) of the vector.

Returns:

the magnitude

magnitude2

public double magnitude2()

Returns the square of the magnitude, without squareroot calculation. This is useful when performance is an issue.

Returns:

the square of the magnitude

normalize

public void normalize()

Modifies the vector to unit magnitude.

getNormalized

public Vector2D getNormalized()

Returns a new vector with magnitude 1 in the direction of the given vector.

Returns:

a unit vector with same direction

getDirection

public double getDirection()

Returns the direction of the vector (range 0..2*pi)

Returns:

the direction of the vector (in radian, zero to east, clockwise)

rotate

public void rotate(double angle)

Rotates the vector by the specified angle.

Parameters:

angle - the rotation angle (in radian, clockwise)

dot

public double dot(Vector2D v)

Returns the scalar product (dot product) of the current vector with the given vector.

Parameters:

v - the vector to take for the dot product

Returns:

the dot product

distanceTo

public double distanceTo(Vector2D v)

Returns the distance between the current vector and the given vector.

Parameters:

v - the vector to take for the distance measurement

Returns:

the distance (magnitude of the vector difference)

add

public Vector2D add(Vector2D v)

Returns a new vector that is the vector sum of the current vector and the given vector. Be aware that the current vector is not modified.

Parameters:

v - the vector to be added to the current vector

Returns:

the sum of the two vectors

invert

public Vector2D invert()

Returns a new vector with inverted coordinates. Be aware that the current vector is not modified.

Returns:

the inverted vector

sub

public Vector2D sub(Vector2D v)

Returns a new vector that is the vector difference of the current vector and the given vector. Be aware that the current vector is not modified.

Parameters:

v - the vector to be substracted from the current vector

Returns:

the difference of the two vectors

mult

public Vector2D mult(int b)

Returns a new vector that is the product by a scalar of the current vector and the given integer. Be aware that the current vector is not modified.

Parameters:

b - the integer scale factor

Returns:

the vector that is scaled with the given integer

mult

public Vector2D mult(float b)

Returns a new vector that is the product by a scalar of the current vector and the given float. Be aware that the current vector is not modified.

Parameters:

b - the float scale factor

Returns:

the vector that is scaled with the given float

mult

public Vector2D mult(double b)

Returns a new vector that is the product by a scalar of the current vector and the given double. Be aware that the current vector is not modified.

Parameters:

b - the double scale factor

Returns:

the vector that is scaled with the given double

clone

public Vector2D clone()

Returns a new vector with the same coordinates as the current vector.

Overrides:

clone in class java.lang.Object

Returns:

a clone of the current vector

toString

public java.lang.String toString()

Returns a string with the x-y-coordinates in the format (x,y).

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the vector

isEqual

public boolean isEqual(Vector2D v)

Returns true, if the current vector is identical to the given vector.

Parameters:

v - the vector to compare

Returns:

true, if both vectors are identical