Hello, could anyone please explain me why the order of wavelets coefficients given on this site: http://wavelets.pybytes.com/wavelet/db4/ is exactly the opposite of that found on this daub.h file that includes the Daubechies coefficients calculated by Kazuo Hatano: http://www.musicdsp.org/showone.php?id=20 I can see that the coefficients are already normalized so divided by 1/sqrt(2) on both. And the signs for the low pass filter case are correct and match between the two. However on pybytes the order of the coefficients is exactly the opposite from h0...h7 on Daubechies 4 (db4), the same is true for the others listed there, to that on daub.h as calculated by Kazuo Hatano (and as it appears in DSP books). What I don't get is if pybytes wrote the coefficients order in the wrong order or if there is a reason why they are listed in reverse order there? Anyone could explain it ? Thank You
Order of Wavelets coefficients....
Started by ●May 5, 2012
Reply by ●May 5, 20122012-05-05
On Saturday, May 5, 2012 9:46:08 AM UTC-7, aredo3606gif wrote:> ... > However on pybytes the order of the coefficients is exactly the opposite > from h0...h7 on Daubechies 4 (db4), the same is true for the others listed > there, to that on daub.h as calculated by Kazuo Hatano (and as it appears > in DSP books). > What I don't get is if pybytes wrote the coefficients order in the wrong > order or if there is a reason why they are listed in reverse order there? >When you apply these coefficients in a calculation do you use a dot-product routine or a convolution routine? Dale B. Dalrymple
Reply by ●May 5, 20122012-05-05
On 5/5/12 4:28 PM, dbd wrote:> On Saturday, May 5, 2012 9:46:08 AM UTC-7, aredo3606gif wrote: >> ... >> However on pybytes the order of the coefficients is exactly the opposite >> from h0...h7 on Daubechies 4 (db4), the same is true for the others listed >> there, to that on daub.h as calculated by Kazuo Hatano (and as it appears >> in DSP books). >> What I don't get is if pybytes wrote the coefficients order in the wrong >> order or if there is a reason why they are listed in reverse order there? >> > > When you apply these coefficients in a calculation do you use a dot-product routine or a convolution routine? >bingo. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."