Package org.djunits.vecmat.d2

Class Matrix2x2Test

java.lang.Object
org.djunits.vecmat.d2.Matrix2x2Test
public class Matrix2x2Test extends Object
Unit tests for Matrix2x2 with concrete quantity Length and unit Length.Unit.

The tests aim for 100% method and branch coverage in Matrix2x2 and the inherited default functionality from:

The assertions are written to reflect the intended functional specification. If any method in the class hierarchy is incorrectly implemented (including TODOs not implemented), tests will fail, as desired.

Conventions used in these tests

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 (specifications); Test implementation by Copilot.

  • Constructor Details

    • Matrix2x2Test

      public Matrix2x2Test()

  • Method Details

    • testFactoryOfArray

      @Test @DisplayName("Factory of(double[]) \u2014 nulls, length check, and SI conversion") public void testFactoryOfArray()
      Verify Matrix2x2.of(double[], Unit) rejects nulls and wrong sizes, and converts using the display unit.

    • testFactoryOfGrid

      @Test @DisplayName("Factory of(double[][]) \u2014 nulls, 2x2 shape, and SI conversion") public void testFactoryOfGrid()
      Verify Matrix2x2.of(double[][], Unit) validation and SI conversion.

    • testInstantiate

      @Test @DisplayName("instantiate(double[]) \u2014 uses provided SI data and keeps display unit") public void testInstantiate()
      Verify Matrix2x2.instantiateSi(double[]) creates a new matrix with the same display unit and the provided SI values.

    • testBasicShapeAndValue

      @Test @DisplayName("rows/cols/value/isRelative") public void testBasicShapeAndValue()
      Verify VectorMatrix.rows(), VectorMatrix.cols(), Table.get(int, int), and relative/absolute flag.

    • testSetDisplayUnit

      @Test @DisplayName("setDisplayUnit() only changes presentation") public void testSetDisplayUnit()
      Verify that VectorMatrix.setDisplayUnit(Unit) only affects presentation and not SI storage.

    • testToString

      @Test @DisplayName("toString() and toString(unit) contain unit abbreviation") public void testToString()
      Call VectorMatrix.toString() and Value.format(Unit) for coverage. We assert the unit abbreviation is present; we do not depend on exact formatting of numbers.

    • testAddSubtractQuantity

      @Test @DisplayName("add(Q) / subtract(Q) apply element-wise SI increments") public void testAddSubtractQuantity()
      Verify VectorMatrix.add(Quantity) and subtract(Q) with quantities.

    • testAddSubtractMatrix

      @Test @DisplayName("add(VM) / subtract(VM) element-wise") public void testAddSubtractMatrix()
      Verify VectorMatrix.add(Quantity) and subtract(VM) with another matrix.

    • testNegateAbsScaleBy

      @Test @DisplayName("negate / abs / scaleBy") public void testNegateAbsScaleBy()
      Verify VectorMatrix.negate(), VectorMatrix.abs(), and VectorMatrix.scaleBy(double).

    • testStats

      @Test @DisplayName("mean / median / min / max / sum") public void testStats()
      Verify mean, median, min, max, and sum.

    • testTranspose

      @Test @DisplayName("transpose() swaps off-diagonals") public void testTranspose()
      Verify transpose on a 2x2 matrix.

    • testDeterminantAndTrace

      @Test @DisplayName("determinantScalar(), determinant(), trace()") public void testDeterminantAndTrace()
      Verify determinant as scalar and as quantity, and trace.

    • testNorms

      @Test @DisplayName("normFrobenius and default norm()") public void testNorms()
      Verify Frobenius norm and default norm().

    • testSymmetry

      @Test @DisplayName("isSymmetric / isSkewSymmetric with and without tolerance") public void testSymmetry()
      Verify symmetry and skew-symmetry checks with and without tolerances.

    • testInverseAndIdentity

      @Test @DisplayName("inverse() and A * A^{-1} \u2248 I") public void testInverseAndIdentity() throws NonInvertibleMatrixException
      Verify Matrix2x2.inverse() and multiplication with its inverse gives the identity (numerically).
      Throws:
      NonInvertibleMatrixException - if inversion fails (test expects success)

    • testInverseThrowsOnSingular

      @Test @DisplayName("inverse() throws on singular matrix") public void testInverseThrowsOnSingular()
      Verify that Matrix2x2.inverse() throws on singular matrices.

    • testAdjugate

      @Test @DisplayName("adjugate() for [[a,b],[c,d]] equals [[d,-b],[-c,a]]") public void testAdjugate()
      Verify Matrix2x2.adjugate() for a generic 2x2 matrix.

    • testMatrixMultiply

      @Test @DisplayName("matrix x matrix multiplication") public void testMatrixMultiply()
      Verify standard 2x2 matrix multiplication.

    • testMatrixTimesVector

      @Test @DisplayName("matrix x vector (column)") public void testMatrixTimesVector()
      Verify multiplication with a column vector. Assumes a Vector2.Col with constructor (double v1, double v2, SIUnit unit) is available.

    • testHadamard

      @Test @DisplayName("Hadamard: invertElements / multiplyElements / divideElements") public void testHadamard()
      Verify Hadamard element-wise operations: invert, multiply, divide.

    • testAs

      @Test @DisplayName("as(targetUnit) success (m\u2194km) and failure (length\u2194time)") public void testAs()
      Verify Matrix2x2.as(Unit) succeeds when SI units match (e.g., m ↔ km), and throws when SI units mismatch (e.g., length ↔ time).

    • testGridExtraction

      @Test @DisplayName("getScalarGrid / getSiGrid") public void testGridExtraction()
      Verify grid extraction helpers on VectorMatrix.

    • testScalarExtraction

      @Test @DisplayName("getScalars / getRowScalars / getColumnScalars / getDiagonalScalars") public void testScalarExtraction()
      Verify scalar array extraction helpers on VectorMatrix.

    • testVectorExtractionSpec

      @Test @DisplayName("getRowVector / getColumnVector / getDiagonalVector return the expected vectors (spec)") public void testVectorExtractionSpec()
      Verify vector extraction helpers (getRow, getColumn, getDiagonal) behave per spec.

      This test expects non-null vectors with the correct content.

    • testSiArrayExtraction

      @Test @DisplayName("getRowSi / getColumnSi / getDiagonalSi") public void testSiArrayExtraction()
      Verify si array extraction helpers on VectorMatrix.

    • testEqualsHashCode

      @Test @DisplayName("equals / hashCode") public void testEqualsHashCode()
      Verify equality and hashCode semantics across VectorMatrix, SquareDenseMatrix, and Matrix2x2.

    • testIndexingAndValues

      @Test @DisplayName("Indexing within bounds and value retrieval") public void testIndexingAndValues()
      Ensure index-related methods do not throw for valid bounds and that value retrieval uses display unit.

    • testMultiplyScalarAs

      @Test public void testMultiplyScalarAs()
      Test multiply/divide by scalar and as() method.

    • testOfDoubleArray

      @Test @DisplayName("of(double[], Unit): nulls, size checks, unit conversion") public void testOfDoubleArray()
      Test Matrix2x2.of(double[], Unit) for nulls, wrong sizes, and unit conversion.

    • testOfSiDoubleArray

      @Test @DisplayName("ofSi(double[], Unit): nulls, size checks, display unit") public void testOfSiDoubleArray()
      Test Matrix2x2.ofSi(double[], Unit) for nulls, wrong sizes, and display unit handling.

    • testOfDoubleGridAllCornerCases

      @Test @DisplayName("of(double[][], Unit): exhaustive null and shape validation") public void testOfDoubleGridAllCornerCases()
      Exhaustive test of Matrix2x2.of(double[][], Unit) grid validation and conversion.

    • testOfSiDoubleGridAllCornerCases

      @Test @DisplayName("ofSi(double[][], Unit): exhaustive null and shape validation") public void testOfSiDoubleGridAllCornerCases()
      Exhaustive test of Matrix2x2.ofSi(double[][], Unit) grid validation.

    • testOfQuantityArray

      @Test @DisplayName("of(Q[]): null elements, wrong length, unit conversion") public void testOfQuantityArray()
      Test Matrix2x2.of(Quantity[]) for nulls, wrong size, and conversion.

    • testOfQuantityGridAllCornerCases

      @Test @DisplayName("of(Q[][]): exhaustive null and shape validation (full branch coverage)") public void testOfQuantityGridAllCornerCases()
      Exhaustive test of Matrix2x2.of(Quantity[][]) grid validation. Covers all branches of: 
       grid == null
 grid.length != 2
 grid[0] == null
 grid[1] == null
 grid[0].length != 2
 grid[1].length != 2
 grid[r][c] == null

    • testAsFunctions

      @Test @DisplayName("Matrix2x2 as() functions test") public void testAsFunctions()
      Test as() functions.