


[H,Gamma] = SMD(R,maxiter,epsilon,Mu,vers);
  Polynomial matrix eigenvalue decomposition (PEVD) algorithm factorising
  a parahermitian matrix represented by R using the sequential matrix
  diagonalisation (SMD) method [1].
  [H,Gamma]=SMD(R) takes as input an MxMx(2L+1) matrix R representing a 
  parahermitian matrix R(z) of the form
     R(z) = RL'z^L + ... + R1' z + R0 + R1 z^{-1} + ... + RLz^{-L}
  whereby
     R(:,:,1) = RL';
     ...
     R(:,:,L) = R1';
     R(:,:,L+1) = R0;
     R(:,:,L+2) = R1;
     ...
     R(:,:,2*L+1) = RL;
  The function returns a paraunitary matrix H(z) in H which creates an 
  approximately diagonalised parahermitian Gamma(z)
     Gamma(z) = H(z) R(z) H~(z).
  The format of Gamma representing Gamma(z) is analogously to R above. For
     H(z) = H0 + H1 z^{-1} + H2 z^{-2} + ...
  the returned parameter H is  
     H(:,:,1) = H0;
     H(:,:,2) = H1;
     H(:,:,3) = H2;
      ...
  SMD will strive of diagonalise and spectrally majorise Gamma(z). The 
  algorithm stops either after a fixed number of iterations or once a 
  threshold for the maximum absolute value of off-diagonal elements has 
  been reached. Default values are outlined below.
  [H,Gamma] = SMD(R,maxiter) stops after maxiter iterations. The default
  value for the optional parameter maxiter is 400.
  [H,Gamma] = SMD(R,maxiter,epsilon) stops either after maxiter iterations
  or once the maximum absolute off-diagonal element has a value smaller than
  epsilon.
  [H,Gamma] = SMD(R,maxiter,epsilon,mu) additionally performs a truncation
  of the parahermitian matrix at every iteration such that matrices at outer
  lags containing a mu-th of the total power are truncated. This stops
  unnecessary growth of the parahermitian matrix, and therefore keeps 
  computational complexity down and Gamma of sufficiently low order.
  [H,Gamma] = SMD(R,maxiter,epsilon,mu,vers) take the optional input vers
  to switch between SMD (vers='SMD') and the coding-gain optimised maximum 
  element SMD (MESMD, vers='MESMD').
  Input parameters:
     R         polynomial covariance matrix
     maxiter   maximum number of iterations (optional)
               default: 400  
     epsilon   stop if largest absolute off-diag element is smaller than 
               epsilon (optional) 
               default: 0.0001  
     mu        power ratio in tail of polynomial matrix to be truncated at 
               every iteration (optional)
               default: 0.0 (only truncating true zeroes)
     vers      SMD version ('SMD' or 'MESMD')
               default: 'SMD'
  Output parameters:
     H         paraunitary matrix
    Gamma      polynomial covariance matrix
  Reference:
  [1] S. Redif, S. Weiss, and J.G. McWhirter, "Sequential Matrix Diagonali-
      sation Algorithms for Polynomial EVD of Parahermitian Matrices," IEEE
      Transactions on Signal Processing, 63(1):81-89, January 2015. 
  Please acknowledge this paper if this function is utilised for academic output.

0001 function [H,Gamma] = SMD(R,maxiter,epsilon,Mu,SFlag); 0002 %[H,Gamma] = SMD(R,maxiter,epsilon,Mu,vers); 0003 % 0004 % Polynomial matrix eigenvalue decomposition (PEVD) algorithm factorising 0005 % a parahermitian matrix represented by R using the sequential matrix 0006 % diagonalisation (SMD) method [1]. 0007 % 0008 % [H,Gamma]=SMD(R) takes as input an MxMx(2L+1) matrix R representing a 0009 % parahermitian matrix R(z) of the form 0010 % R(z) = RL'z^L + ... + R1' z + R0 + R1 z^{-1} + ... + RLz^{-L} 0011 % whereby 0012 % R(:,:,1) = RL'; 0013 % ... 0014 % R(:,:,L) = R1'; 0015 % R(:,:,L+1) = R0; 0016 % R(:,:,L+2) = R1; 0017 % ... 0018 % R(:,:,2*L+1) = RL; 0019 % The function returns a paraunitary matrix H(z) in H which creates an 0020 % approximately diagonalised parahermitian Gamma(z) 0021 % Gamma(z) = H(z) R(z) H~(z). 0022 % The format of Gamma representing Gamma(z) is analogously to R above. For 0023 % H(z) = H0 + H1 z^{-1} + H2 z^{-2} + ... 0024 % the returned parameter H is 0025 % H(:,:,1) = H0; 0026 % H(:,:,2) = H1; 0027 % H(:,:,3) = H2; 0028 % ... 0029 % SMD will strive of diagonalise and spectrally majorise Gamma(z). The 0030 % algorithm stops either after a fixed number of iterations or once a 0031 % threshold for the maximum absolute value of off-diagonal elements has 0032 % been reached. Default values are outlined below. 0033 % 0034 % [H,Gamma] = SMD(R,maxiter) stops after maxiter iterations. The default 0035 % value for the optional parameter maxiter is 400. 0036 % 0037 % [H,Gamma] = SMD(R,maxiter,epsilon) stops either after maxiter iterations 0038 % or once the maximum absolute off-diagonal element has a value smaller than 0039 % epsilon. 0040 % 0041 % [H,Gamma] = SMD(R,maxiter,epsilon,mu) additionally performs a truncation 0042 % of the parahermitian matrix at every iteration such that matrices at outer 0043 % lags containing a mu-th of the total power are truncated. This stops 0044 % unnecessary growth of the parahermitian matrix, and therefore keeps 0045 % computational complexity down and Gamma of sufficiently low order. 0046 % 0047 % [H,Gamma] = SMD(R,maxiter,epsilon,mu,vers) take the optional input vers 0048 % to switch between SMD (vers='SMD') and the coding-gain optimised maximum 0049 % element SMD (MESMD, vers='MESMD'). 0050 % 0051 % Input parameters: 0052 % R polynomial covariance matrix 0053 % maxiter maximum number of iterations (optional) 0054 % default: 400 0055 % epsilon stop if largest absolute off-diag element is smaller than 0056 % epsilon (optional) 0057 % default: 0.0001 0058 % mu power ratio in tail of polynomial matrix to be truncated at 0059 % every iteration (optional) 0060 % default: 0.0 (only truncating true zeroes) 0061 % vers SMD version ('SMD' or 'MESMD') 0062 % default: 'SMD' 0063 % 0064 % Output parameters: 0065 % H paraunitary matrix 0066 % Gamma polynomial covariance matrix 0067 % 0068 % Reference: 0069 % 0070 % [1] S. Redif, S. Weiss, and J.G. McWhirter, "Sequential Matrix Diagonali- 0071 % sation Algorithms for Polynomial EVD of Parahermitian Matrices," IEEE 0072 % Transactions on Signal Processing, 63(1):81-89, January 2015. 0073 % 0074 % Please acknowledge this paper if this function is utilised for academic output.