function [x,t,Dn,w]=ctfs_synthesis(T0,N,Dnfxn,t,arg1,arg2,arg3)
%%% Function to implement CT Fourier series synthesis equation
%%%
%%%   [x,t]=ctfs_synthesis(T0,N,Dnfxn,t,arg1,arg2,arg3);
%%%    
%%%   Variables:
%%%        T0 = fundamental period
%%%         N = number of Fourier series coefficients to use
%%%     Dnfxn = string containing name of function to compute FS
%%%             coefficients.  This function takes one argument:  the n
%%%             vector.  
%%%         t = vector of times [OPTIONAL; if no times are specified
%%%                              function computes values for 2 periods]
%%%      arg1 = OPTIONAL first argument to send to the function specified 
%%%             by Dnfxn 
%%%      arg2 = OPTIONAL second argument to send to the function specified 
%%%             by Dnfxn 
%%%      arg3 = OPTIONAL third argument to send to the function specified 
%%%             by Dnfxn 
%%%         x = x(t)
%%%

if nargin<3
  error('CTFS_SYNTHESIS:  not enough input arguments')
elseif nargin<4 | isempty(t)
  if N>0
    maxfreq=N/T0;
  else
    maxfreq=1/T0;
  end
  t=-T0:1/(8*maxfreq):T0; % if t not specified, sample at four times Nyquist
end

w0=2*pi/T0;				% Fundamental frequency
n=-N:N;					% Vector of n's

En=exp(j*t'*n*w0);			% Matrix of complex exponentials

%%% Call the function to generate the Fourier series coefficients
if nargin==5
  Dn=feval(Dnfxn,n,arg1);		% 1 optional argument specified
elseif nargin==6
  Dn=feval(Dnfxn,n,arg1,arg2);		% 2 optional arguments specified
elseif nargin==7
  Dn=feval(Dnfxn,n,arg1,arg2,arg3);	% 3 optional arguments specified
else
  Dn=feval(Dnfxn,n);			% No optional arguments specified
end
  
Dn=Dn(:);				% Make sure Dn is column vector
w=n*w0;

x=En*Dn;				% Compute x as matrix multiply

%%% Note:  100*eps is on order of 2*10^(-14).  This is needed to deal
%%% with impulse train calculations.  You'll still get imaginary values
%%% if you use lots of coefficients for the impulse train.

if max(abs(imag(x)))<100*eps		% Make sure x is real
  x=real(x);				% (eliminate small imaginary part)
end


return