quadcof

 Helper function to calculate the nonstationary quadratic inverse matrix
 Usage: [A,sumV] = quadcof(N,NW,order)
 N             (number of samples)
 NW: Time bandwidth product
 order: order (number of coefficients, upto 4NW)

 Outputs: 

 A: quadratic inverse coefficient matrix
 sumV: sum of the quadratic inverse eigenvectors

0001 function [A,sumV] = quadcof(N,NW,order)
0002 % Helper function to calculate the nonstationary quadratic inverse matrix
0003 % Usage: [A,sumV] = quadcof(N,NW,order)
0004 % N             (number of samples)
0005 % NW: Time bandwidth product
0006 % order: order (number of coefficients, upto 4NW)
0007 %
0008 % Outputs:
0009 %
0010 % A: quadratic inverse coefficient matrix
0011 % sumV: sum of the quadratic inverse eigenvectors
0012 
0013 A = zeros(2*NW,2*NW,order);
0014 V = quadinv(N,NW);
0015 [P,alpha] = dpss(N,NW,'calc');
0016 
0017 for ii = 1:order
0018 
0019   for jj = 1:2*NW
0020     for kk = 1:2*NW
0021     A(jj,kk,ii) = sqrt(alpha(jj)*alpha(kk))*...
0022                       sum(P(:,jj).*P(:,kk).*V(:,ii));
0023     end;
0024   end;
0025 end;
0026 sumV=sum(V)/N;
0027 
0028