How to calculate the energy of details and approxmiations coefficients of discret wavelet transform ?

2 次查看(过去 30 天)
Hi everyone, i calculate the energy of details and approxmiations coefficients of discret wavelet transform .i used DWT(Daub4) Here is the code
for n=1:23
deriv=(val(n,:))/2.559375;
t=(0:length(deriv)-1)/Fs;
result{n} = filtfilt(d1,deriv);
[c,l]=wavedec(result{n},4,'db4');
[cd1,cd2,cd3,cd4]=detcoef(c,l,[1,2,3,4]);
cA4=appcoef(c,l,'db4',4);
[Ea,Ed]=wenergy(c,l)
energie{n} = {Ea, Ed};
end
And when i was looking for the formula of the energy i found this :
and as i understand the energy is the percentage of energy corresponding to the approximation and the details
So when i was trying to write a C code using this formula and the values of cd1,cd2,cd3,cd4 i don't get the same values that i have with matlab So i want to know where i wrong ?
i mean to calcuate the energy i should use [cd1,cd2,cd3,cd4]??
Please i need a clarification,Thanks
  2 个评论
Sandeep Nayak
Sandeep Nayak 2019-11-8
yes. cd1,cd2,cd3,cd4 are the details coefficients and the command wenergy gives the percentage of energy not the actual energy. you can calculate the percentage energy by the expression i.e. percentage energy due to approximation = (energy of approximation-energy of details)/energy of approximation *100. similarly % energy due to details = 100-% energy due to approximation. energy of approximation is sum of square of approximation coefficients and energy of details is sum of square of details coefficients. Hope you got your answer..

请先登录,再进行评论。

回答(0 个)

类别

Help CenterFile Exchange 中查找有关 Continuous Wavelet Transforms 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by