wavelets

[Do Dinh Nghia <don@iem.pw.edu.pl>]

Cha`o ca'c ba.n!

To^i co' mo^t. va^n' dde^` muo^n' ddu*o*c. ca'c ban. giu'p ddo*~.
DDo' la` so-called "wavelets & wavelet transformation"
To^i dda~ co' trong tay cuo^n' "Approximation Theory,Wavelets & Applications"
nhu*ng qua? tha^t. to^i ddo.c kho' qu'a vi vo^n' di~ chi? la` nha` ky~ thua^t.
ma` NATO ANSI Series do ca'c nha` toa'n vie^'t , kha' la` triu` tu*o*ng.(ddo^i'
vo*i' to^i).
Bie^n' ddo^i? Fourier thi` chung' to^i , nhu*ng~ nha` ky~ thua^t. dda~ quen 
va` dda~ co' thua^t. toan' bie^n' ddo^i? Fourier nhanh (FFT) , tha^m. tri' trongMATLAB co' le^nh. FFT va` IFFT(inverce) . Ba?n cha^t' cua? bie^n' ddo^i? Fourierla`xap xi? hoa'(approximation) mo^t. ti'n hie^u. (trong ky~ thua^t.) hay mo^t. ham`ba(ng` nhu*ng~ thanh` pha^`n tua^n` hoan` (harmonic components) co' ca'c ta^`n so^' kha'c nhau.The^' co`n WT thi` approximate ti'n hie^u. ra sao?
 Gia? su*? ta co' mo^t. chuo^i~ so^' X=[x1 x2 ....xn]T thi` bie^n' ddo^i? WT
cua? X o* scale s nhu* the^s nao`? Co' cha(ng mo^t. thua^t. toan' bie^n' ddo^i?
nhanh ?
 Ra^t' mong nha^.n ddu*o*c. su*. giu'p ddo*~ cua? cac' ban. Chao`!