shh.csparse
Class P2Matrix

Object
  Matrix
      ElemMatrix
          P2Matrix

public final class P2Matrix

extends ElemMatrix

The class of n × n permutation matrices of order two.

Author:

Mark McConnell

Constructor Summary

P2Matrix(int i, int j)
Constructs a square matrix with entries i,j and j,i equal to 1, with k,k equal to 1 for all k different from both of i,j, and with 0's elsewhere.

Method Summary

int	det() The determinant, as an int ±1.
SparseElt	get(int i0, int j0) Returns a SparseElt whose value is the i,j value of the matrix.
Matrix	inverse() Check the implementation for whether it's supported, and whether it's destructive.
boolean	isIdentity() Whether this is an n × n identity matrix.
Matrix	mult(Matrix b) If b is a CSparse or DenseMatrixZ, is destructive to it; otherwise is unsupported.
Matrix	multOnRight(Matrix b) If b is a CSparse or DenseMatrixZ, is destructive to it; otherwise is unsupported.
String	toString() Formats the matrix with each column left-justified.
Matrix	transpose() Non-destructive.

Methods inherited from class ElemMatrix

add, getNumCols, getNumRows, isProductZero, isZero, set

Methods inherited from class Object

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

Constructor Detail

P2Matrix

public P2Matrix(int i,
                int j)

Constructs a square matrix with entries i,j and j,i equal to 1, with k,k equal to 1 for all k different from both of i,j, and with 0's elsewhere.

Throws:

IllegalArgumentException - If i = j.

Method Detail

det

public final int det()

Description copied from class: ElemMatrix

The determinant, as an int ±1.

Specified by:

det in class ElemMatrix

get

public SparseElt get(int i0,
                     int j0)

Description copied from class: Matrix

Returns a SparseElt whose value is the i,j value of the matrix. May return null for a zero entry. The index of the SparseElt is unspecified--there is no guarantee it is either i or j.

Specified by:

get in class Matrix

inverse

public final Matrix inverse()

Description copied from class: Matrix

Check the implementation for whether it's supported, and whether it's destructive.

Specified by:

inverse in class Matrix

isIdentity

public final boolean isIdentity()

Description copied from class: Matrix

Whether this is an n × n identity matrix.

Specified by:

isIdentity in class Matrix

mult

public Matrix mult(Matrix b)

If b is a CSparse or DenseMatrixZ, is destructive to it; otherwise is unsupported.

Specified by:

mult in class Matrix

multOnRight

public Matrix multOnRight(Matrix b)

If b is a CSparse or DenseMatrixZ, is destructive to it; otherwise is unsupported.

Specified by:

multOnRight in class ElemMatrix

See Also:

Matrix.mult(shh.csparse.Matrix)

toString

public String toString()

Description copied from class: Matrix

Formats the matrix with each column left-justified.

Overrides:

toString in class Matrix

transpose

public final Matrix transpose()

Description copied from class: Matrix

Non-destructive.

Specified by:

transpose in class Matrix