Package org.djunits.vecmat.def

Class SquareDenseMatrix<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>>

java.lang.Object

org.djunits.vecmat.def.VectorMatrix<Q,T,SI,H,TT>

org.djunits.vecmat.def.Table<Q,M,SI,H,MT>

org.djunits.vecmat.def.Matrix<Q,M,SI,H,M>

org.djunits.vecmat.def.SquareMatrix<Q,M,SI,H>

org.djunits.vecmat.def.SquareDenseMatrix<Q,M,SI,H>

Type Parameters:

Q - the quantity type

M - the 'SELF' square dense matrix type

SI - the square dense matrix type with generics <SIQuantity, SIUnit<

H - the generic square dense matrix type with generics <?, ?< for Hadamard operations

All Implemented Interfaces:

Serializable, Additive<M>, Scalable<M>, Value<M,Q>, Hadamard<H,SI>

Direct Known Subclasses:

Matrix1x1, Matrix2x2, Matrix3x3

public abstract class SquareDenseMatrix<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>>
extends SquareMatrix<Q,M,SI,H>

SquareDenseMatrix implements the core functions for a matrix with n x n real-valued entries. The data is stored in a dense double[] field. The matrix is immutable, except for the display unit, which can be changed.

Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://djunits.org. The DJUNITS project is distributed under a three-clause BSD-style license.

Author:

Alexander Verbraeck

See Also:

• Serialized Form

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SquareDenseMatrix(double[] dataSi, Unit<?,Q> displayUnit, int order)	Create a new SquareDenseMatrix with a unit.

Method Summary

Modifier and Type	Method	Description
int	cols()	Return the number of columns.
boolean	equals(Object obj)
double[]	getColumnSi(int col)	Return an array with SI-values for the given column (0-based) from the table or matrix.
double[]	getRowSi(int row)	Return an array with SI-values for the given row (0-based) from the table or matrix.
double[]	getSiArray()	Return a row-major array of SI-values for this matrix or vector.
int	hashCode()
int	nonZeroCount()	Return the number of non-zero entries in the vector, matrix or table.
int	rows()	Return the number of rows.
double	si(int row, int col)	Return the si-value at position (row, col), where both row and col are 0-based values.
double[]	unsafeSiArray()	Return a row-major possibly UNSAFE array of SI-values for this matrix or vector.

Methods inherited from class org.djunits.vecmat.def.SquareMatrix

adjugate, determinant, determinantSi, getDiagonalScalars, getDiagonalSi, getDiagonalVector, inverse, isSkewSymmetric, isSkewSymmetric, isSymmetric, isSymmetric, normFrobenius, order, trace, transpose

Methods inherited from class org.djunits.vecmat.def.Matrix

format, format, format, multiply

Methods inherited from class org.djunits.vecmat.def.Table

checkCol, checkRow, get, getColumnScalars, getColumnVector, getRowScalars, getRowVector, getScalarArray, getScalarGrid, getSiGrid, mcheckCol, mcheckRow, mget, mgetColumnScalars, mgetColumnSi, mgetColumnVector, mgetRowScalars, mgetRowSi, mgetRowVector, msi

Methods inherited from class org.djunits.vecmat.def.VectorMatrix

abs, add, add, asMatrix1x1, asMatrix2x2, asMatrix3x3, asMatrixNxM, asMatrixNxN, asQuantityTable, asVector1, asVector2Col, asVector2Row, asVector3Col, asVector3Row, asVectorNCol, asVectorNRow, checkMultiply, checkMultiply, divideElements, divideEntries, getDisplayUnit, instantiateSi, instantiateSi, invertEntries, isRelative, max, mean, median, min, multiplyElements, multiplyEntries, multiplyEntries, negate, nnz, scaleBy, setDisplayUnit, subtract, subtract, sum, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.djunits.vecmat.operations.Hadamard

divideEntries

Methods inherited from interface org.djunits.value.Scalable

divideBy

Methods inherited from interface org.djunits.value.Value

isAbsolute, setDisplayUnit

Constructor Details

SquareDenseMatrix

protected SquareDenseMatrix(double[] dataSi,
 Unit<?,Q> displayUnit,
 int order)

Create a new SquareDenseMatrix with a unit. NO SAFE COPY of the double[] data element is made.

Parameters:

dataSi - the matrix values {a11, a12, ..., a21, a22, ...} expressed in the SI unit

displayUnit - the display unit to use

order - the order of the square matrix (number of rows/columns)

Throws:

IllegalArgumentException - when dataSi.length != order * order.

Method Details

unsafeSiArray

public double[] unsafeSiArray()

Description copied from class: VectorMatrix

Return a row-major possibly UNSAFE array of SI-values for this matrix or vector. The method might give access to the underlying data structure, so treat the data carefully.

Specified by:

unsafeSiArray in class VectorMatrix<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Returns:

the row-major array of SI-values (safe copy)

getSiArray

public double[] getSiArray()

Description copied from class: VectorMatrix

Return a row-major array of SI-values for this matrix or vector. This is guaranteed to be a safe copy.

Specified by:

getSiArray in class VectorMatrix<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Returns:

the row-major array of SI-values (safe copy)

si

public double si(int row,
 int col)

Description copied from class: Table

Return the si-value at position (row, col), where both row and col are 0-based values.

Specified by:

si in class Table<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Parameters:

row - the row (0-based)

col - the column (0-based)

Returns:

the si-value at position (row, col)

rows

public int rows()

Description copied from class: VectorMatrix

Return the number of rows.

Specified by:

rows in class VectorMatrix<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Returns:

the number of rows

cols

public int cols()

Description copied from class: VectorMatrix

Return the number of columns.

Specified by:

cols in class VectorMatrix<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Returns:

the number of columns

nonZeroCount

public int nonZeroCount()

Description copied from class: VectorMatrix

Return the number of non-zero entries in the vector, matrix or table. Note that NaN and Infinity count as a non-zero element. The value -0.0 counts as 0.0.

Specified by:

nonZeroCount in class VectorMatrix<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Returns:

the number of non-zero entries in the vector, matrix or table

getRowSi

public double[] getRowSi(int row)

Description copied from class: Table

Return an array with SI-values for the given row (0-based) from the table or matrix.

Specified by:

getRowSi in class Table<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Parameters:

row - the row number to retrieve (0-based)

Returns:

an array with SI-values with the data at the given row

getColumnSi

public double[] getColumnSi(int col)

Description copied from class: Table

Return an array with SI-values for the given column (0-based) from the table or matrix.

Specified by:

getColumnSi in class Table<Q extends Quantity<Q>,M extends SquareDenseMatrix<Q,M,SI,H>,SI extends SquareDenseMatrix<SIQuantity,SI,?,?>,H extends SquareDenseMatrix<?,?,?,?>,M extends SquareDenseMatrix<Q,M,SI,H>>

Parameters:

col - the column number to retrieve (0-based)

Returns:

an array with SI-values with the data at the given column

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object