shh.csparse
Class DenseMatrixZ

Object
  Matrix
      DenseMatrixZ

All Implemented Interfaces:

Cloneable

public class DenseMatrixZ

extends Matrix

implements Cloneable

Matrices over Z using BigIntegers, implemented as m × n arrays in a straightforward way. In addition to the basic methods, the LLL algorithm is available at doLLL().

Author:

Mark McConnell

Field Summary

protected BigInteger[][]

a Holds the entries.

Constructor Summary

DenseMatrixZ(int n)
Constructs an n × n identity matrix.

DenseMatrixZ(int m, int n)
Constructs an m × n zero matrix.

Method Summary

Matrix	add(Matrix b0) Adds this and another DenseMatrixZ, returning a DenseMatrixZ.
Object	clone()
int	doLLL() Does LLL reduction on the columns, destructively, using Cohen, Algorithm 2.7.2 (see reference in NumThy).
SparseElt	get(int i, int j) Returns a SparseElt whose value is the i,j value of the matrix.
int	getNumCols() Returns the number n of columns.
int	getNumRows() Returns the number m of rows.
Matrix	inverse() Unsupported.
boolean	isIdentity() Whether this is an n × n identity matrix.
boolean	isProductZero(Matrix b0) Silly implementation that stores the entire product.
boolean	isZero() Whether every entry in this matrix is zero.
static void	main(String[] args) Tests doLLL().
Matrix	mult(Matrix b0) Non-destructive if b0 is a CSparse or DenseMatrixZ, destructive to this if b0 is an ElemMatrix.
void	set(int i, int j, BigInteger val) Easier to use in this class than set(SparseElt, int).
void	set(SparseElt rowIndexAndVal, int colIndex) Set method.
Matrix	transpose() Non-destructive.

Methods inherited from class Matrix

toString

Methods inherited from class Object

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

Field Detail

a

protected final BigInteger[][] a

Holds the entries.

Constructor Detail

DenseMatrixZ

public DenseMatrixZ(int m,
                    int n)

Constructs an m × n zero matrix.

DenseMatrixZ

public DenseMatrixZ(int n)

Constructs an n × n identity matrix.

Method Detail

add

public Matrix add(Matrix b0)

Adds this and another DenseMatrixZ, returning a DenseMatrixZ. Does not support other classes of b0. Non-destructive.

Specified by:

add in class Matrix

Throws:

IllegalArgumentException - If the dimensions don't match.

get

public SparseElt get(int i,
                     int j)

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

getNumCols

public int getNumCols()

Description copied from class: Matrix

Returns the number n of columns.

Specified by:

getNumCols in class Matrix

getNumRows

public int getNumRows()

Description copied from class: Matrix

Returns the number m of rows.

Specified by:

getNumRows in class Matrix

inverse

public Matrix inverse()

Unsupported.

Specified by:

inverse in class Matrix

isIdentity

public boolean isIdentity()

Description copied from class: Matrix

Whether this is an n × n identity matrix.

Specified by:

isIdentity in class Matrix

isZero

public boolean isZero()

Description copied from class: Matrix

Whether every entry in this matrix is zero.

Specified by:

isZero in class Matrix

mult

public Matrix mult(Matrix b0)

Non-destructive if b0 is a CSparse or DenseMatrixZ, destructive to this if b0 is an ElemMatrix.

Specified by:

mult in class Matrix

Throws:

IllegalArgumentException - If the inner dimensions don't match.

ClassCastException - If not all entries of b0 are over Z (i.e., of class SparseEltZ).

isProductZero

public boolean isProductZero(Matrix b0)

Silly implementation that stores the entire product. Unsupported unless b0 is of class CSparse or DenseMatrixZ.

Specified by:

isProductZero in class Matrix

set

public void set(SparseElt rowIndexAndVal,
                int colIndex)

Set method.

Specified by:

set in class Matrix

Throws:

ClassCastException - If the first argument isn't a SparseEltZ.

set

public final void set(int i,
                      int j,
                      BigInteger val)

Easier to use in this class than set(SparseElt, int).

transpose

public Matrix transpose()

Description copied from class: Matrix

Non-destructive.

Specified by:

transpose in class Matrix

clone

public Object clone()

doLLL

public int doLLL()

Does LLL reduction on the columns, destructively, using Cohen, Algorithm 2.7.2 (see reference in NumThy).

Returns:

kerdim = the dim of the kernel. The columns j ≥ kerdim are a Q-basis (and I think in fact a Z-basis) of the lattice generated by the columns of the original matrix.

main

public static void main(String[] args)

Tests doLLL(). Input: m n entry0 entry1 entry2, and so on. The entries are placed in a matrix in row-major order, repeating if necessary.