TVec.DCT Methods

Summary

The forward discrete cosine transform (DCT).

Class
TVec

Declaration

Function DCT(Vec: TVec): TVec;

Description

Calculates the forward discrete cosine transform (DCT) of the Vec and writes the result in the calling vector. If Vec.Length is a power of 2, the function uses an efficient algorithm that is significantly faster than the direct computation of DCT. For other values of Vec Length, this function uses the direct formulas.

Declaration

Function DCT: TVec;

Description

Calculates the forward discrete cosine transform (DCT) of all calling vector elements in-place. If vector Length is a power of 2, the function uses an efficient algorithm that is significantly faster than the direct computation of DCT. For different lengths this function uses the direct formulas given below; however, the symmetry of cosine function is taken into account, which allows to perform about half of the multiplication operations in the formulas. In the following definition of DCT, N=Vec.Length and V is the calling vector:

See Also
IDCT
IDCT
FFT
TDenseMtxVec.IDCT
TDenseMtxVec.IDCT
TDenseMtxVec.FFT

Example 1

        var a,b: TVec;
        begin
          CreateIt(a,b);
          a.SetIt(False,[1,-2,3,4]);
          b.DCT(a);
          FreeIt(a,b);
        end;