Add a class related to the IMF's instantaneous frequency

[YihaoSu]

This issue is to add a class for calculating the instantaneous frequency and amplitude of a IMF.

[ZhaoShaw]

Hi，
I have some questions about the example you give. Does the variables iamp and ifreq represent the instantaneous amplitude (or instantaneous phase?) , and the instantaneous frequency of the signal (structure signal, Z(t)=X(t)+iY(t)) ?

[YihaoSu]

Yes. The instance of class HSA has two attributes (variables): iamp (instantaneous amplitude of a signal) and ifreq (instantaneous frequency of a signal). This class calls the MATLAB function 'fa' to calculate these variables. You can find the source code of 'fa' function in /Path to your Python site-packages/hhtpywrapper-0.1.dev0-py3.6.egg/hhtpywrapper/HHT_MATLAB_package/HSA/fa.m

You can read the paper 'On instantaneous frequency' and the doc of MATLAB hilbert function to understand how the 'fa' function calculate instantaneous amplitudes and frequencies .

[ZhaoShaw]

Thank you for your answer!
I have read the matlab source code but I have not been able to read hilbert.m carefully before. Meanwhile, thank you for your recommendation, I will read it with my free time!