All Implemented Interfaces:

Serializable, Cloneable, LenientComparable, Matrix
```
public final class Matrix2
extends MatrixSIS
```
A matrix of fixed 2×2 size, typically resulting from MathTransform2D derivative computation. The matrix members are:
```
 ┌         ┐
 │ m00 m01 │
 │ m10 m11 │
 └         ┘
```
Since:

0.4

See Also:

Matrix1, Matrix3, Matrix4, Serialized Form

Defined in the sis-referencing module

Field Summary

Fields
Modifier and Type	Field	Description
`double`	`m00`	The first matrix element in the first row.
`double`	`m01`	The second matrix element in the first row.
`double`	`m10`	The first matrix element in the second row.
`double`	`m11`	The second matrix element in the second row.
`static int`	`SIZE`	The matrix size, which is 2.

Constructor Summary

Constructors
Constructor	Description
`Matrix2()`	Creates a new identity matrix.
`Matrix2(double[] elements)`	Creates a new matrix initialized to the specified values.
`Matrix2(double m00, double m01, double m10, double m11)`	Creates a new matrix initialized to the specified values.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static Matrix2`	`castOrCopy(Matrix matrix)`	Casts or copies the given matrix to a `Matrix2` implementation.
`boolean`	`equals(Object object)`	Returns `true` if the specified object is of type `Matrix2` and all of the data members are equal to the corresponding data members in this matrix.
`double`	`getElement(int row, int column)`	Retrieves the value at the specified row and column of this matrix.
`double[]`	`getElements()`	Returns all matrix elements in a flat, row-major (column indices vary fastest) array.
`int`	`getNumCol()`	Returns the number of columns in this matrix, which is always 2 in this implementation.
`int`	`getNumRow()`	Returns the number of rows in this matrix, which is always 2 in this implementation.
`int`	`hashCode()`	Returns a hash code value based on the data values in this object.
`boolean`	`isAffine()`	Returns `true` if this matrix represents an affine transform.
`boolean`	`isIdentity()`	Returns `true` if this matrix is an identity matrix.
`void`	`normalizeColumns()`	Normalizes all columns in-place.
`void`	`setElement(int row, int column, double value)`	Modifies the value at the specified row and column of this matrix.
`void`	`setElements(double[] elements)`	Sets all matrix elements from a flat, row-major (column indices vary fastest) array.
`void`	`transpose()`	Sets the value of this matrix to its transpose.

Methods inherited from class MatrixSIS
clone, convertAfter, convertBefore, equals, equals, getNumber, inverse, multiply, multiply, removeColumns, removeRows, setMatrix, setNumber, solve, toString, translate

Methods inherited from class Object
finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - SIZE
```
public static final int SIZE
```
    The matrix size, which is 2.
    
    See Also:
    
    Constant Field Values
  - m00
```
public double m00
```
    The first matrix element in the first row.
  - m01
```
public double m01
```
    The second matrix element in the first row.
  - m10
```
public double m10
```
    The first matrix element in the second row.
  - m11
```
public double m11
```
    The second matrix element in the second row.
- Constructor Detail
  - Matrix2
```
public Matrix2()
```
    Creates a new identity matrix.
  - Matrix2
```
public Matrix2(double m00,
               double m01,
               double m10,
               double m11)
```
    Creates a new matrix initialized to the specified values.
    
    Parameters:
    
    m00 - the first matrix element in the first row.
    
    m01 - the second matrix element in the first row.
    
    m10 - the first matrix element in the second row.
    
    m11 - the second matrix element in the second row.
  - Matrix2
```
public Matrix2(double[] elements)
        throws IllegalArgumentException
```
    Creates a new matrix initialized to the specified values. The length of the given array must be 4 and the values in the same order than the above constructor.
    
    Parameters:
    
    elements - elements of the matrix. Column indices vary fastest.
    
    Throws:
    
    IllegalArgumentException - if the given array does not have the expected length.
    
    See Also:
    
    setElements(double[]), Matrices.create(int, int, double[])
- Method Detail
  - castOrCopy
```
public static Matrix2 castOrCopy(Matrix matrix)
                          throws MismatchedMatrixSizeException
```
    Casts or copies the given matrix to a Matrix2 implementation. If the given matrix is already an instance of Matrix2, then it is returned unchanged. Otherwise this method verifies the matrix size, then copies all elements in a new Matrix2 object.
    
    Parameters:
    
    matrix - the matrix to cast or copy, or null.
    
    Returns:
    
    the matrix argument if it can be safely casted (including null argument), or a copy of the given matrix otherwise.
    
    Throws:
    
    MismatchedMatrixSizeException - if the size of the given matrix is not 2×2.
  - getNumRow
```
public final int getNumRow()
```
    Returns the number of rows in this matrix, which is always 2 in this implementation.
    
    Returns:
    
    always 2.
  - getNumCol
```
public final int getNumCol()
```
    Returns the number of columns in this matrix, which is always 2 in this implementation.
    
    Returns:
    
    always 2.
  - getElement
```
public final double getElement(int row,
                               int column)
```
    Retrieves the value at the specified row and column of this matrix. This method can be invoked when the matrix size or type is unknown. If the matrix is known to be an instance of Matrix2, then the m00 … m11 fields can be read directly for efficiency.
    
    Specified by:
    
    getElement in interface Matrix
    
    Specified by:
    
    getElement in class MatrixSIS
    
    Parameters:
    
    row - the row index, which can only be 0 or 1.
    
    column - the column index, which can only be 0 or 1.
    
    Returns:
    
    the current value at the given row and column.
  - setElement
```
public final void setElement(int row,
                             int column,
                             double value)
```
    Modifies the value at the specified row and column of this matrix. This method can be invoked when the matrix size or type is unknown. If the matrix is known to be an instance of Matrix2, then the m00 … m11 fields can be set directly for efficiency.
    
    Parameters:
    
    row - the row index, which can only be 0 or 1.
    
    column - the column index, which can only be 0 or 1.
    
    value - the new value to set at the given row and column.
  - getElements
```
public final double[] getElements()
```
    Returns all matrix elements in a flat, row-major (column indices vary fastest) array. The array length is 4.
    
    Overrides:
    
    getElements in class MatrixSIS
    
    Returns:
    
    a copy of all current matrix elements in a row-major array.
  - setElements
```
public final void setElements(double[] elements)
```
    Sets all matrix elements from a flat, row-major (column indices vary fastest) array. The array length shall be 4.
    
    Specified by:
    
    setElements in class MatrixSIS
    
    Parameters:
    
    elements - The new matrix elements in a row-major array.
    
    See Also:
    
    Matrices.create(int, int, double[])
  - isAffine
```
public final boolean isAffine()
```
    Returns true if this matrix represents an affine transform. A transform is affine if the matrix is square and its last row contains only zeros, except in the last column which contains 1.
    
    Overrides:
    
    isAffine in class MatrixSIS
    
    Returns:
    
    true if this matrix represents an affine transform.
    
    See Also:
    
    Matrices.isAffine(Matrix), LinearTransform.isAffine()
  - isIdentity
```
public final boolean isIdentity()
```
    Returns true if this matrix is an identity matrix. This method is equivalent to the following code, except that it is potentially more efficient:
    return Matrices.isIdentity(this, 0.0);
    Specified by:
    
    isIdentity in interface Matrix
    
    Specified by:
    
    isIdentity in class MatrixSIS
    
    Returns:
    
    true if this matrix is an identity matrix.
    
    See Also:
    
    Matrices.isIdentity(Matrix, double), AffineTransform.isIdentity()
  - transpose
```
public void transpose()
```
    Sets the value of this matrix to its transpose.
    
    Specified by:
    
    transpose in class MatrixSIS
  - normalizeColumns
```
public void normalizeColumns()
```
    Normalizes all columns in-place. Each columns in this matrix is considered as a vector. For each column (vector), this method computes the magnitude (vector length) as the square root of the sum of all square values. Then, all values in the column are divided by that magnitude.
    This method is useful when the matrix is a transform derivative. In such matrix, each column is a vector representing the displacement in target space when an coordinate in the source space is increased by one. Invoking this method turns those vectors into unitary vectors, which is useful for forming the basis of a new coordinate system.
    
    Overrides:
    
    normalizeColumns in class MatrixSIS
  - equals
```
public boolean equals(Object object)
```
    Returns true if the specified object is of type Matrix2 and all of the data members are equal to the corresponding data members in this matrix.
    
    Specified by:
    
    equals in interface LenientComparable
    
    Overrides:
    
    equals in class MatrixSIS
    
    Parameters:
    
    object - the object to compare with this matrix for equality.
    
    Returns:
    
    true if the given object is equal to this matrix.
    
    See Also:
    
    ComparisonMode.STRICT
  - hashCode
```
public int hashCode()
```
    Returns a hash code value based on the data values in this object.
    
    Overrides:
    
    hashCode in class MatrixSIS
    
    Returns:
    
    a hash code value for this matrix.

Class Matrix2

Field Summary

Constructor Summary

Method Summary

Methods inherited from class MatrixSIS

Methods inherited from class Object

Field Detail

SIZE

m00

m01

m10

m11

Constructor Detail

Matrix2

Matrix2

Matrix2

Method Detail

castOrCopy

getNumRow

getNumCol

getElement

setElement

getElements

setElements

isAffine

isIdentity

transpose

normalizeColumns

equals

hashCode