DoubleMatrixItem(Int32) Property

Gets or sets the element of this instance corresponding to the specified linear index.

Definition

Namespace: Novacta.Analytics
Assembly: Novacta.Analytics (in Novacta.Analytics.dll) Version: 2.1.0+428f3840cfab98dda567bb0ed350b302533e273a

C#

public double this[
	int linearIndex
] { get; set; }

VB

Public Default Property Item ( 
	linearIndex As Integer
) As Double
	Get
	Set

C++

public:
virtual property double default[int linearIndex] {
	double get (int linearIndex) sealed;
	void set (int linearIndex, double value) sealed;
}

F#

abstract Item : float with get, set
override Item : float with get, set

Parameters

linearIndex Int32: The zero-based linear index of the element to get or set.

Property Value

Double
The element corresponding to the specified linear index.

Implements

IListTItemInt32
IReadOnlyListTItemInt32

Remarks

Let LaTeX equation be a matrix, and consider its generic entry

where and are the number of rows and columns of , respectively.

A linear index completely identifies an entry, assuming that entries are linearly ordered following the ColumnMajor data order. This means that entry LaTeX equation has linear index equal to , and matrix entries can be enumerated as follows:

where is the Count of the matrix.

Example

In the following example, a matrix element is accessed using its linear index.

C#

using System;

namespace Novacta.Analytics.CodeExamples
{
    public class LinearIndexerExample0  
    {
        public void Main()
        {
            // Create a matrix.
            var data = new double[6] {
                10, 20, 30,
                40, 50, 60
            };
            var matrix = DoubleMatrix.Dense(2, 3, data, StorageOrder.RowMajor);
            Console.WriteLine("Initial data matrix:");
            Console.WriteLine(matrix);

            // Specify a linear index.
            int linearIndex = 3;
            Console.WriteLine();
            Console.WriteLine("Linear index: {0}", linearIndex);

            // Set the corresponding entry.
            matrix[linearIndex] = -50.0;

            Console.WriteLine();
            Console.WriteLine("Updated data matrix:");
            Console.WriteLine(matrix);

            // Entries can also be accessed using a read-only wrapper of the matrix.
            ReadOnlyDoubleMatrix readOnlyMatrix = matrix.AsReadOnly();

            Console.WriteLine();
            Console.WriteLine("Updated matrix entry:");
            Console.WriteLine(readOnlyMatrix[linearIndex]);
        }
    }
}

// Executing method Main() produces the following output:
// 
// Initial data matrix:
// 10               20               30               
// 40               50               60               
// 
// 
// 
// Linear index: 3
// 
// Updated data matrix:
// 10               20               30               
// 40               -50              60               
// 
// 
// 
// Updated matrix entry:
// -50

Exceptions

ArgumentOutOfRangeException

linearIndex is less than zero.
-or-
linearIndex is equal to or greater than the Count of this instance.