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function G=framematrix(F,L);
%FRAMEMATRIX Frame analysis operator matrix
% Usage: G=framematrix(F,L);
%
% `G=framematrix(F,L)` returns the matrix representation *G* of the frame
% analysis operator for a frame *F* of length *L*. The frame object *F*
% must have been created using |frame|_.
%
% The frame analysis operator matrix contains all the frame atoms as
% column vectors. It has dimensions $L \times Ncoef$, where $Ncoef$ is the
% number of coefficients. The number of coefficients can be found as
% `Ncoef=framered(F)*L`. This means than the frame matrix is usually
% **very** large, and this routine should only be used for small values of
% *L*.
%
% The action of the frame transform operator |frana|_ is equal to
% multiplication with the Hermitean transpose of the frame
% matrix. Consider the following simple example:::
%
% L=200;
% F=frame('dgt','gauss',10,20);
% G=framematrix(F,L);
% testsig = randn(L,1);
% res = frana(F,testsig)-G'*testsig;
% norm(res)
%
% See also: frame, frana, frsyn
if nargin<2
error('%s: Too few input parameters.',upper(mfilename));
end;
if F.realinput
error(['%s: The synthesis operator of real-valued-input frames does is ' ...
'non-linear and does not have a matrix represenation.']);
else
Lcheck=framelength(F,L);
if Lcheck~=L
error('%s: Incompatible frame length.',upper(mfilename));
end;
% Generic code handles all frames where there are no extra coefficients
% in the representation
Ncoef=framered(F)*L;
coef=eye(Ncoef);
G = frsyn(F,coef);
end;

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