/// <summary>
        /// Checks that the specified <see cref="ComplexMatrix"/>
        /// instances are equal.
        /// </summary>
        /// <param name="expected">The expected matrix.</param>
        /// <param name="actual">The actual matrix.</param>
        /// <param name="delta">The required accuracy.</param>
        public static void AreEqual(
            ComplexMatrix expected,
            ComplexMatrix actual,
            double delta)
        {
            // Null references ?

            Assert.IsNotNull(expected);
            Assert.IsNotNull(actual);

            // Matrix Fields

            object expectedImplementor = Reflector.GetField(
                expected,
                "implementor");

            Assert.IsNotNull(expectedImplementor);

            var expectedColumnMajorOrderedEntries =
                (Complex[])Reflector.ExecuteMember(
                    expectedImplementor,
                    "AsColumnMajorDenseArray",
                    null);

            Assert.IsNotNull(expectedColumnMajorOrderedEntries);

            object actualImplementor = Reflector.GetField(
                actual,
                "implementor");

            Assert.IsNotNull(actualImplementor);

            var actualColumnMajorOrderedEntries =
                (Complex[])Reflector.ExecuteMember(
                    actualImplementor,
                    "AsColumnMajorDenseArray",
                    null);

            Assert.IsNotNull(actualColumnMajorOrderedEntries);

            Assert.AreEqual(
                expectedColumnMajorOrderedEntries.Length,
                actualColumnMajorOrderedEntries.Length);

            for (int l = 0; l < actualColumnMajorOrderedEntries.Length; l++)
            {
                ComplexAssert.AreEqual(
                    expectedColumnMajorOrderedEntries[l],
                    actualColumnMajorOrderedEntries[l],
                    ComplexMatrixTest.Accuracy);
            }

            int expectedNumberOfRows = (int)Reflector.GetProperty(
                expectedImplementor,
                "NumberOfRows");

            int actualNumberOfRows = (int)Reflector.GetProperty(
                actualImplementor,
                "NumberOfRows");

            Assert.AreEqual(expectedNumberOfRows, actualNumberOfRows);

            int expectedNumberOfColumns = (int)Reflector.GetProperty(
                expectedImplementor,
                "NumberOfColumns");

            int actualNumberOfColumns = (int)Reflector.GetProperty(
                actualImplementor,
                "NumberOfColumns");

            Assert.AreEqual(expectedNumberOfColumns, actualNumberOfColumns);

            // Matrix Names

            MatrixNamesAreEqual(expected, actual);
        }
        /// <summary>
        /// Determines whether the specified matrix has the expected state.
        /// </summary>
        /// <param name="expectedState">The expected state.</param>
        /// <param name="actualMatrix">The actual matrix.</param>
        /// <param name="delta">The required precision.</param>
        public static void IsStateAsExpected(
            ComplexMatrixState expectedState,
            ComplexMatrix actualMatrix,
            double delta)
        {
            // Null reference ?

            Assert.IsNotNull(actualMatrix);

            // Matrix Fields

            object implementor = Reflector.GetField(
                actualMatrix,
                "implementor");

            Assert.IsNotNull(implementor);

            Complex[] actualColumnMajorOrderedEntries;

            actualColumnMajorOrderedEntries =
                (Complex[])Reflector.ExecuteMember(
                    implementor,
                    "AsColumnMajorDenseArray",
                    null);

            Assert.IsNotNull(actualColumnMajorOrderedEntries);

            var expectedColumnMajorOrderedEntries = expectedState.AsColumnMajorDenseArray;

            Assert.AreEqual(
                expectedColumnMajorOrderedEntries.Length,
                actualColumnMajorOrderedEntries.Length);

            for (int Id = 0; Id < actualColumnMajorOrderedEntries.Length; Id++)
            {
                ComplexAssert.AreEqual(
                    expectedColumnMajorOrderedEntries[Id],
                    actualColumnMajorOrderedEntries[Id],
                    delta);
            }

            int actualNumberOfRows = (int)Reflector.GetProperty(
                implementor,
                "NumberOfRows");

            int expectedNumberOfRows = expectedState.NumberOfRows;

            Assert.AreEqual(expectedNumberOfRows, actualNumberOfRows);

            int actualNumberOfColumns = (int)Reflector.GetProperty(
                implementor,
                "NumberOfColumns");

            int expectedNumberOfColumns = expectedState.NumberOfColumns;

            Assert.AreEqual(expectedNumberOfColumns, actualNumberOfColumns);

            // Matrix Names

            // Matrix name

            Assert.AreEqual(expectedState.Name, actualMatrix.Name);

            // Row names

            // Both have row names
            bool expectedHasRowNames = expectedState.RowNames is not null;

            Assert.AreEqual(expectedHasRowNames, actualMatrix.HasRowNames);

            if (expectedHasRowNames)
            {
                CompareDimensionNames("row", expectedState.RowNames, actualMatrix.RowNames);
            }

            // Column names

            // Both have column names
            bool expectedHasColumnNames = expectedState.ColumnNames is not null;

            Assert.AreEqual(expectedHasColumnNames, actualMatrix.HasColumnNames);

            if (expectedHasColumnNames)
            {
                CompareDimensionNames("column", expectedState.ColumnNames, actualMatrix.ColumnNames);
            }
        }
        /// <summary>
        /// Determines whether the specified target has the
        /// expected state.
        /// </summary>
        /// <param name="target">The target.</param>
        /// <param name="expectedFeatureVariables">
        /// The expected feature variables.</param>
        /// <param name="expectedResponseVariable">
        /// The expected response variable.</param>
        /// <param name="expectedFeaturePremises">
        /// The expected feature premises.</param>
        /// <param name="expectedResponseConclusion">
        /// The expected response conclusion.</param>
        /// <param name="expectedTruthValue">
        /// The expected truth value.</param>
        /// <exception cref="AssertFailedException">
        /// Target categorical entailment has an unexpected state.
        /// </exception>
        public static void IsStateAsExpected(
            CategoricalEntailment target,
            IReadOnlyList <CategoricalVariable> expectedFeatureVariables,
            CategoricalVariable expectedResponseVariable,
            IReadOnlyList <SortedSet <double> > expectedFeaturePremises,
            double expectedResponseConclusion,
            double expectedTruthValue)
        {
            if (target.FeatureVariables.Count != expectedFeatureVariables.Count)
            {
                throw new AssertFailedException(
                          "The list of target feature variables has an unexpected count.");
            }

            for (int i = 0; i < expectedFeatureVariables.Count; i++)
            {
                CategoricalVariableAssert.AreEqual(
                    expectedFeatureVariables[i],
                    target.FeatureVariables[i]);
            }

            CategoricalVariableAssert.AreEqual(
                expectedResponseVariable,
                target.ResponseVariable);

            var targetFeaturePremises =
                (List <SortedSet <double> >)Reflector.GetField(target, "featurePremises");

            for (int i = 0; i < expectedFeaturePremises.Count; i++)
            {
                if (!expectedFeaturePremises[i].SetEquals(
                        target.FeaturePremises[i]))
                {
                    throw new AssertFailedException(
                              "The target feature premises are not as expected.");
                }

                if (!expectedFeaturePremises[i].SetEquals(
                        targetFeaturePremises[i]))
                {
                    throw new AssertFailedException(
                              "The target feature premises are not as expected.");
                }
            }

            bool[] expectedIsProperPremise = new bool[expectedFeaturePremises.Count];
            for (int i = 0; i < expectedFeaturePremises.Count; i++)
            {
                expectedIsProperPremise[i] = !(
                    expectedFeaturePremises[i].Count == 0
                    ||
                    expectedFeaturePremises[i].Count == expectedFeatureVariables[i].NumberOfCategories);
            }

            bool[] actualIsProperPremise =
                (bool[])Reflector.GetField(target, "isNonemptyProperPremise");

            ArrayAssert <bool> .AreEqual(
                expected : expectedIsProperPremise,
                actual : actualIsProperPremise);

            Assert.AreEqual(
                expected: expectedResponseConclusion,
                actual: target.ResponseConclusion,
                delta: DoubleMatrixTest.Accuracy);

            Assert.AreEqual(
                expected: expectedTruthValue,
                actual: target.TruthValue,
                delta: DoubleMatrixTest.Accuracy);
        }