TMtx.DetectMtxType Method

Summary

Determines type of the matrix.

Class
TMtx

Declaration

Function DetectMtxType(CheckPosDef: boolean = False): TMtxType;

Description

Tests the calling matrix and returns the type of the calling of matrix. The following types are supported:

mtSymmPosDef = symmetric positive definite matrix
mtSymmetric = symmetric matrix
mtHermPosDef = Hermitian positive definite matrix
mtHermitian = Hermitian matrix
mtTriangle = triangular matrix, with unit or non unit main diagonal
mtGeneral = general matrix (none of the above)

Checking for positive definite matrix can be very expensive (O(n) = 1/3*n^3). Therefore the ChekPosDef parameter is False by default, unless the user specifies otherwise. The method will not detect banded matrix storage.

Example 1

      var X,B: TVec;
          A: TMtx;
          at: TMtxType;
      begin
        CreateIt(X,B);
        CreateIt(A);
        try
          B.SetIt(false,[0,2]);
          A.SetIt(2,2,false,[1,2,
                  2,4]);  // 2x2 real matrix

          at := A.DetectMtxType;
          A.LUSolve(B,X,at);
          // This is the same for this example (except slower)
          A.LUSolve(B,X,mtSymmetric);
          // You could also specify
          A.AutoMtxType := True
          A.LUSolve(B,X);  // the type is autodetected
        finally
          FreeIt(B,X);
          FreeIt(A);
        end;
      end;