如何避免大型动态对象的装箱/拆箱？

Question

I need to multiply two relatively large matrices and do it many times (in a loop). However, the format (type of objects) how these matrices are stored in the memory should be chosen by user. There are three possibilities:

1. double [,] M1; double [,] M2; ( two-dimensional arrays)

2. double[][] M1; double [][]M2; ( jagged arrays).

3. Matrix <double> M1;Matrix <double> M2; ( Math Net Numerics format).

Each format suits a corresponding method ( taken from a numerical library as you may have already guessed). I need to avoid boxing and unboxing at all cost ( since its expensive) so the following code will not work for me ( unless you tell me that boxing/unboxing is cheaper than fast matrix multiplication):

object M1;
object M2;

switch case 
{
    case 1:
        M1 = new double[rows,columns];
    .../etc
}

One way to solve it is very straightforward: just to declare 6 matrices( 6 variables) and at runtime initialize two of them. But this looks ugly and will make the code much more complicated.

My question: is there any elegant solution of this problem? I am new to C# but the searching over the site did not help me much.

Answer 1

Yes, you are all right, there is no boxing/unboxing here. I figured out what I want and need to do. I will create an interface which declares some matrix methods:

interface MatrixMethods
{
   void MatrixIni();
   void DoMultiplication();
   double ReturnFinalResult();
// etc
}

Then I will use a generic class:

class MatrixStorage <T> 
{
  protected T M1;
  protected T M2;
// etc
}

and finally the needed class:

    class MatrixMult<T> : MatrixStorage<T> , MatrixMethods
{
    public void MatrixIni()
    {
        //etc Matrix random ini
    }
    public void DoMultiplication()
    {
        // multiplication
    }
    public double ReturnFinalResult()
    {
        // compute output
    }
    MatrixMult(params int[] input)
    {
        // ini
    }

}

and, then I instantiate the class and do calculations:

MatrixMethods newMatrixMult;
newMatrixMult = new MatrixMult<UserMatrixType>(userData);
newMatrixMult.DoMultiplication();
double result = newMatrixMult.ReturnFinalResult

I apologize for a misleading question. Best