DoubleMatrixMultiply(DoubleMatrix, DoubleMatrix) Operator

Determines the product of two matrices.

Definition

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

C#

public static DoubleMatrix operator *(
	DoubleMatrix left,
	DoubleMatrix right
)

VB

Public Shared Operator * ( 
	left As DoubleMatrix,
	right As DoubleMatrix
) As DoubleMatrix

C++

public:
static DoubleMatrix^ operator *(
	DoubleMatrix^ left, 
	DoubleMatrix^ right
)

F#

static let inline (*)
        left : DoubleMatrix * 
        right : DoubleMatrix  : DoubleMatrix

Parameters

left DoubleMatrix: The left operand.
right DoubleMatrix: The right operand.

Return Value

DoubleMatrix
The result of multiplying left by right.

Remarks

Let LaTeX equation and be the left number of rows and columns, respectively, and consider its generic entry

Analogously, Let and be the right number of rows and columns, respectively, and let its generic entry given by

LaTeX equation

The method operates as follows.

If left is scalar, then the method returns a matrix having the same dimensions of right, whose generic entry is:
If right is scalar, then the method returns a matrix having the same dimensions of left, whose generic entry is:
If neither left nor right is scalar, then the method returns a matrix whose generic entry is

provided that the number of columns of left agrees with the number of rows of right; otherwise, an exception is thrown.

Example

In the following example, some matrices are multiplied.

C#

using System;

namespace Novacta.Analytics.CodeExamples
{
    public class MultiplicationExample0  
    {
        public void Main()
        {
            // Create the left operand.
            var data = new double[4] {
                0,  2,  
                1,  3
            };
            var left = DoubleMatrix.Dense(2, 2, data, StorageOrder.RowMajor);
            Console.WriteLine("left =");
            Console.WriteLine(left);

            // Create the right operand.
            data = [
                0,  20,  40,
               10,  30,  50
            ];
            var right = DoubleMatrix.Dense(2, 3, data, StorageOrder.RowMajor);
            Console.WriteLine("right =");
            Console.WriteLine(right);

            // Multiply left by right.
            var result = left * right;

            Console.WriteLine();
            Console.WriteLine("left * right =");
            Console.WriteLine(result);

            // In .NET languages that do not support overloaded operators,
            // you can use the alternative methods named Multiply.
            result = DoubleMatrix.Multiply(left, right);

            Console.WriteLine();
            Console.WriteLine("DoubleMatrix.Multiply(left, right) returns");
            Console.WriteLine();
            Console.WriteLine(result);

            // Both operators and alternative methods are overloaded to 
            // support read-only matrix arguments.
            // Compute the product using a read-only wrapper of left.
            ReadOnlyDoubleMatrix readOnlyLeft = left.AsReadOnly();
            result = readOnlyLeft * right;

            Console.WriteLine();
            Console.WriteLine("readOnlyLeft * right =");
            Console.WriteLine(result);
        }
    }
}

// Executing method Main() produces the following output:
// 
// left =
// 0                2                
// 1                3                
// 
// 
// right =
// 0                20               40               
// 10               30               50               
// 
// 
// 
// left * right =
// 20               60               100              
// 30               110              190              
// 
// 
// 
// DoubleMatrix.Multiply(left, right) returns
// 
// 20               60               100              
// 30               110              190              
// 
// 
// 
// readOnlyLeft * right =
// 20               60               100              
// 30               110              190              
// 
//

Exceptions

ArgumentNullException	left is null. -or- right is null.
ArgumentException	Both left and right are not scalar matrices, and the number of columns of left is not equal to the number of rows of right.