[Nonfractal-commits] how to define the scale range

[You, Wonsang]

Hello Huibin,

1. Let f_N be the Nyquist frequency. The wavelet scale j is related to the frequency range [f_N/2^{j+1}, f_N/2^j]. So, if the sample rate = 1 second and you set up the option range=[1, 5], it would correspond to the frequency range [0.015625, 0.5] Hz.

2. The signal length should be a power of 2 in DWT. However, the input signal to bfn_mfin_ml is not necessary to have the length of power of 2 since it will automatically truncate the signal; for example, the signal with 100 will be truncated as 2^6=64.

I wish it is helpful for you. Thank you.

Best Regards,
Wonsang


From: nonfractal-commits-bounces at www.nitrc.org [mailto:nonfractal-commits-bounces at www.nitrc.org] On Behalf Of Hui-bin Jia
Sent: Monday, October 16, 2017 10:33 AM
To: nonfractal-commits <nonfractal-commits at www.nitrc.org>
Subject: [Nonfractal-commits] how to define the scale range

Dear Wonsang,
      I have only limited knowledge about DWT. In the function bfn_mfin_ml we need to define the scale range. I think this option is used to define the frequency range in Hurst estimation.
Usually, the frequency range in fMRI analysis is defined to be [0.01 0.1] Hz. Could you give me some tips about how to define the scale range according to the frequency range?

In some papers, the authors argue that the signal length should be a power of 2 in order to obtain DWT-based Hurst exponent. I'm asking whether the signal length should be a power of 2 in function bfn_mfin_ml?

Thank you!

Best Regards,
Huibin Jia

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