org.spaceroots.mantissa.linalg

Class LowerTriangularMatrix

java.lang.Object

org.spaceroots.mantissa.linalg.Matrix

org.spaceroots.mantissa.linalg.SquareMatrix

org.spaceroots.mantissa.linalg.LowerTriangularMatrix

All Implemented Interfaces:

java.io.Serializable

public class LowerTriangularMatrix
extends SquareMatrix

This class implements lower triangular matrices of linear algebra.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
LowerTriangularMatrix(int order) Simple constructor.
LowerTriangularMatrix(int order, double[] data) Simple constructor.
LowerTriangularMatrix(LowerTriangularMatrix l) Copy constructor.

Method Summary

Modifier and Type	Method and Description
Matrix	duplicate() Polymorphic copy operator.
double	getDeterminant(double epsilon) Get the determinant of the matrix.
org.spaceroots.mantissa.linalg.NonNullRange	getRangeForColumn(int j) Set a range to the non null part covered by a column.
org.spaceroots.mantissa.linalg.NonNullRange	getRangeForRow(int i) Set a range to the non null part covered by a row.
void	selfAdd(LowerTriangularMatrix l) Add a matrix to the instance.
void	selfSub(LowerTriangularMatrix l) Substract a matrix from the instance.
void	setElement(int i, int j, double value) Set a matrix element.
Matrix	solve(Matrix b, double epsilon) Solve the A.X = B equation.

Methods inherited from class org.spaceroots.mantissa.linalg.SquareMatrix

getInverse, solve

Methods inherited from class org.spaceroots.mantissa.linalg.Matrix

add, getColumns, getElement, getRows, getTranspose, mul, mul, selfMul, sub, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

LowerTriangularMatrix

public LowerTriangularMatrix(int order)

Simple constructor. This constructor builds a lower triangular matrix of specified order, all elements being zeros.

Parameters:

order - order of the matrix

LowerTriangularMatrix

public LowerTriangularMatrix(int order,
                             double[] data)

Simple constructor. Build a matrix with specified elements.

Parameters:

order - order of the matrix

data - table of the matrix elements (stored row after row)

LowerTriangularMatrix

public LowerTriangularMatrix(LowerTriangularMatrix l)

Copy constructor.

Parameters:

l - lower triangular matrix to copy

Method Detail

duplicate

public Matrix duplicate()

Description copied from class: Matrix

Polymorphic copy operator. This method build a new object of the same type of the instance. It is somewhat similar to the Object.clone() method, except that it has public access, it doesn't throw any specific exception and it returns a Matrix.

Specified by:

duplicate in class Matrix

See Also:

Object.clone()

setElement

public void setElement(int i,
                       int j,
                       double value)

Description copied from class: Matrix

Set a matrix element.

Overrides:

setElement in class Matrix

Parameters:

i - row index, from 0 to rows - 1

j - column index, from 0 to cols - 1

value - value of the element

See Also:

Matrix.getElement(int, int)

selfAdd

public void selfAdd(LowerTriangularMatrix l)

Add a matrix to the instance. This method adds a matrix to the instance. It does modify the instance.

Parameters:

l - lower triangular matrix to add

Throws:

java.lang.IllegalArgumentException - if there is a dimension mismatch

selfSub

public void selfSub(LowerTriangularMatrix l)

Substract a matrix from the instance. This method substract a matrix from the instance. It does modify the instance.

Parameters:

l - lower triangular matrix to substract

Throws:

java.lang.IllegalArgumentException - if there is a dimension mismatch

getDeterminant

public double getDeterminant(double epsilon)

Description copied from class: SquareMatrix

Get the determinant of the matrix.

Specified by:

getDeterminant in class SquareMatrix

Parameters:

epsilon - threshold on matrix elements below which the matrix is considered singular (this is used by the derived classes that use a factorization to compute the determinant)

Returns:

the determinant of the matrix

solve

public Matrix solve(Matrix b,
                    double epsilon)
             throws SingularMatrixException

Description copied from class: SquareMatrix

Solve the A.X = B equation.

Specified by:

solve in class SquareMatrix

Parameters:

b - second term of the equation

epsilon - threshold on matrix elements below which the matrix is considered singular

Returns:

a matrix X such that A.X = B, where A is the instance

Throws:

SingularMatrixException - if the matrix is singular

getRangeForRow

public org.spaceroots.mantissa.linalg.NonNullRange getRangeForRow(int i)

Description copied from class: Matrix

Set a range to the non null part covered by a row.

Parameters:

i - index of the row

Returns:

range of non nul elements in the specified row

See Also:

Matrix.getRangeForColumn(int)

getRangeForColumn

public org.spaceroots.mantissa.linalg.NonNullRange getRangeForColumn(int j)

Description copied from class: Matrix

Set a range to the non null part covered by a column.

Parameters:

j - index of the column

Returns:

range of non nul elements in the specified column

See Also:

Matrix.getRangeForRow(int)