Need code to find standard deviation?

how to find SD of a signal (double) using all mothers wavelets (all available in wavelet 1-D) at only 6th level of decomposition. For now I am using wavelet analyzer which is consuming so much time. I want results like:

Mother Wavelet SD

haar 0.07341

db1 0.07341

db2 0.03707

db3 0.0263

db4 0.0342

db5 0.03597

db6 0.02833

db7 0.03212

db8 0.03629

db9 0.03118

db10 0.03043

sym2 0.03707

sym3 0.0263

Answer 1

[Tejas]

Hello Muhammad,

To calculate the standard deviation of level 6 decomposition of a signal, using multiple wavelets, try these steps:

• Start by declaring the list of wavelets to be used.

    signal = randn(1, 1000); %Replace this with your input signal
    waveletList = {'haar', 'db1', 'db2', 'db3', 'db4', 'db5', 'db6', 'db7', 'db8', 'db9', 'db10', 'sym2', 'sym3'};

• For each wavelet, use the 'wavedec' function to decompose the signal, the 'detcoef' function to find the coefficients, and the 'std' function to determine the standard deviation.

    for i = 1:length(waveletList)
        waveletName = waveletList{i};
        [C, L] = wavedec(signal, 6, waveletName);
        D6 = detcoef(C, L, 6);
        sd = std(D6);
        fprintf('%s  %.5f\n', waveletName, sd)
    end

For a better understanding of the solution, refer to these documentations:

• wavedec: https://www.mathworks.com/help/wavelet/ref/wavedec.html
• detcoef: https://www.mathworks.com/help/wavelet/ref/detcoef.html
• std: https://www.mathworks.com/help/matlab/ref/double.std.html