com.numericalmethod.suanshu.matrix.doubles.matrixtype.dense.diagonal
Class DiagonalMatrix

java.lang.Object
  com.numericalmethod.suanshu.matrix.doubles.matrixtype.MatrixMathImpl<T>
      com.numericalmethod.suanshu.matrix.doubles.matrixtype.MatrixStorageImpl<T>
          com.numericalmethod.suanshu.matrix.doubles.matrixtype.dense.diagonal.DiagonalMatrix

All Implemented Interfaces:

DeepCopyable, AbelianGroup<Matrix>, Monoid<Matrix>, Ring<Matrix>, Matrix, MatrixAccessor, MatrixRing, Densifiable, MatrixDimension

public class DiagonalMatrix
extends MatrixStorageImpl<T>

This class represents a matrix with non-zero entries only on the main diagonal.

See Also:

Wikipedia: Diagonal matrix

Constructor Summary

DiagonalMatrix(DiagonalMatrix that)
Copy constructor.

DiagonalMatrix(double[] data)
Construct a diagonal matrix from a double[] array.

DiagonalMatrix(int dim)
Construct a diagonal matrix of dimension dim * dim.

Method Summary

DiagonalMatrix	add(DiagonalMatrix that) this + that Add with a DiagonalMatrix.
DiagonalMatrix	deepCopy() The implementation can return an instance created from this by the copy constructor of the class, or just this if the instance itself is immutable.
DenseVector	diagonal() Get a copy of the diagonal of the matrix.
boolean	equals(java.lang.Object obj) Check if two matrices (of different implementations) are equal.
DenseVector	getColumn(int col) Get a specified column as a vector.
DenseVector	getRow(int row) Get a specified row as a vector.
int	hashCode()
DiagonalMatrix	minus(DiagonalMatrix that) this - that Subtract a DiagonalMatrix.
DiagonalMatrix	multiply(DiagonalMatrix that) this %*% that Multiply by a DiagonalMatrix.
Vector	multiply(Vector v) Right multiply this matrix, A by a vector.
DiagonalMatrix	ONE() Get an identity matrix that has the same dimension as this matrix.
DiagonalMatrix	scaled(double scalar) scalar * this
DenseVector	subDiagonal() Get a copy of the sub-diagonal of the matrix.
DenseVector	superDiagonal() Get a copy of the super-diagonal of the matrix.
DiagonalMatrix	t() The transpose of a diagonal matrix is the same as itself.
DenseMatrix	toDense() Densify a matrix, i.e., convert a matrix implementation to a standard dense matrix, DenseMatrix.
java.lang.String	toString()
DiagonalMatrix	ZERO() The additive element 0 in the group, such that for all elements a in the group, the equation 0 + a = a + 0 = a holds.

Methods inherited from class com.numericalmethod.suanshu.matrix.doubles.matrixtype.MatrixStorageImpl

get, getMatrixData, set, setMatrixData

Methods inherited from class com.numericalmethod.suanshu.matrix.doubles.matrixtype.MatrixMathImpl

add, call, getSample, minus, multiply, nCols, nRows, opposite, setColumn, setColumn, setRow, setRow

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

DiagonalMatrix

public DiagonalMatrix(double[] data)

Construct a diagonal matrix from a double[] array.

For example,

         new double[][]{
              {1, 2, 3, 4, 5},
          }
 

is

              | 1  0  0  0  0 |
              | 0  2  0  0  0 |
              | 0  0  3  0  0 |
              | 0  0  0  4  0 |
              | 0  0  0  0  5 |
 

Parameters:

data - the 1D array input

DiagonalMatrix

public DiagonalMatrix(int dim)

Construct a diagonal matrix of dimension dim * dim.

Parameters:

dim - dimension; for a square matrix, it is the number of rows or columns

DiagonalMatrix

public DiagonalMatrix(DiagonalMatrix that)

Copy constructor.

Parameters:

that - a DiagonalMatrix

Method Detail

deepCopy

public DiagonalMatrix deepCopy()

Description copied from interface: Matrix

The implementation can return an instance created from this by the copy constructor of the class, or just this if the instance itself is immutable.

Override the return type.

Returns:

an independent copy of Matrix instance

add

public DiagonalMatrix add(DiagonalMatrix that)

this + that

Add with a DiagonalMatrix.

Parameters:

that - another matrix

Returns:

the sum of this and that

minus

public DiagonalMatrix minus(DiagonalMatrix that)

this - that

Subtract a DiagonalMatrix.

Parameters:

that - another matrix

Returns:

the difference between this and that

multiply

public DiagonalMatrix multiply(DiagonalMatrix that)

this %*% that

Multiply by a DiagonalMatrix.

Parameters:

that - another matrix

Returns:

the product of this and that

multiply

public Vector multiply(Vector v)

Description copied from interface: Matrix

Right multiply this matrix, A by a vector.

Specified by:

multiply in interface Matrix

Overrides:

multiply in class MatrixMathImpl<DiagonalMatrix>

Parameters:

v - a vector

Returns:

A %*% v

scaled

public DiagonalMatrix scaled(double scalar)

Description copied from interface: Matrix

scalar * this

Specified by:

scaled in interface Matrix

Overrides:

scaled in class MatrixMathImpl<DiagonalMatrix>

Parameters:

scalar - a double

Returns:

scalar * this

t

public DiagonalMatrix t()

The transpose of a diagonal matrix is the same as itself.

Specified by:

t in interface MatrixRing

Overrides:

t in class MatrixMathImpl<DiagonalMatrix>

Returns:

a copy

ZERO

public DiagonalMatrix ZERO()

Description copied from interface: AbelianGroup

The additive element 0 in the group, such that for all elements a in the group, the equation

0 + a = a + 0 = a

holds.

Returns:

0

ONE

public DiagonalMatrix ONE()

Description copied from interface: MatrixRing

Get an identity matrix that has the same dimension as this matrix.

For a non-square matrix, it zeros out the rows (columns) with index > nCols (nRows).

Returns:

an identity matrix

toDense

public DenseMatrix toDense()

Description copied from interface: Densifiable

Densify a matrix, i.e., convert a matrix implementation to a standard dense matrix, DenseMatrix.

This is equivalent to

new DenseMatrix(Matrix A)

Individual matrix implementation may optimize the conversion by taking advantage of having access to the class' private members. In other words, toDense() is in general more efficient than explicit copy construction.

As an example, for some long matrix computations, we may not be sure about the return type. We can always cast it to the standard matrix. That is,

DenseMatrix A = B.multiply(C).add(D).minus(E).toDense();

This statement always works regardless of the types of B, C, D, and E.

Specified by:

toDense in interface Densifiable

Returns:

a matrix representation in DenseMatrix

diagonal

public DenseVector diagonal()

Get a copy of the diagonal of the matrix.

Returns:

a copy of the diagonal

superDiagonal

public DenseVector superDiagonal()

Get a copy of the super-diagonal of the matrix.

Returns:

a copy of the super-diagonal

subDiagonal

public DenseVector subDiagonal()

Get a copy of the sub-diagonal of the matrix.

Returns:

a copy of the sub-diagonal

getRow

public DenseVector getRow(int row)

Description copied from interface: MatrixAccessor

Get a specified row as a vector.

Specified by:

getRow in interface MatrixAccessor

Overrides:

getRow in class MatrixMathImpl<T extends com.numericalmethod.suanshu.matrix.doubles.matrixtype.dense.diagonal.DiagonalDataMatrix>

Parameters:

row - the row index

Returns:

a vector A[row, ]

getColumn

public DenseVector getColumn(int col)

Description copied from interface: MatrixAccessor

Get a specified column as a vector.

Specified by:

getColumn in interface MatrixAccessor

Overrides:

getColumn in class MatrixMathImpl<T extends com.numericalmethod.suanshu.matrix.doubles.matrixtype.dense.diagonal.DiagonalDataMatrix>

Parameters:

col - the column index

Returns:

a vector A[, col]

toString

public java.lang.String toString()

Overrides:

toString in class MatrixMathImpl<T extends com.numericalmethod.suanshu.matrix.doubles.matrixtype.dense.diagonal.DiagonalDataMatrix>

equals

public boolean equals(java.lang.Object obj)

Description copied from class: MatrixStorageImpl

Check if two matrices (of different implementations) are equal. They are equal iff two matrices have the same values, entry-by-entry.

Overrides:

equals in class MatrixStorageImpl<T extends com.numericalmethod.suanshu.matrix.doubles.matrixtype.dense.diagonal.DiagonalDataMatrix>

Returns:

true iff two matrices have the same values, entry-by-entry

hashCode

public int hashCode()

Overrides:

hashCode in class MatrixStorageImpl<T extends com.numericalmethod.suanshu.matrix.doubles.matrixtype.dense.diagonal.DiagonalDataMatrix>