Octave/MATLAB code for Global signal extraction

• example.m: example script file
  It makes plots of mixing coefficients and extracted signal.
  How to use
  
  1. Download example.m, getA.m and extg.m
  2. From MATLAB or Octave,
     >> example
  
  
• getA.m: function file to estimate the mixing vector a from data matrix X.
  Usage: [ea esnr eainit] = getA(X,threshold,maxiter)
  outputs -
  
  • ea: estimated a (ea.^2 is estimated power)
  • esnr: estimated SNR
  • eainit: estimated a before ALS
  inputs -
  • X: n-by-T data matrix, n:channel, T:sample size
  • threshold: Threshold of the alternating least square (default=10^(-6))
  • maxiter: Maximum number of iteration in ALS. (default=1000)
  
  
• extg.m: function file to extract the global signal from mixing coefficients a and data matrix X.
  Usage: [eg w] = extg(a,X)
  Outputs -
  • eg: estimated global signal g
  • w: estimated optimal weight
  Inputs -
  • a: mixing coefficients, n-by-1 vector, n:# of channel
  • X: n-by-T data matrix, T:sample size
  
  
• ALS_mex.c: MEX file to calculate ALS faster. This is an option for getA.m.
  How to install
  1. Compile mex file
     --MATLAB--

     >> mex ALS_mex.c
     

     --Octave 2.9.9-- from propmt,

     % mkoctfile --mex ALS_mex.c
     

  2. Modify getA.m, line 63.
     if 1 --> if 0