% -*- texinfo -*-
% @deftypefn {Function File} {irsa_actcore.m}
% [@var{rfyp},@var{err}] = irsa_actcore (@var{xpn}, @var{yp},
% @var{fmaxn}, [@var{itmax}], [@var{thresh}])
%
% Reconstruction of the frequency representation (i.e. the spectrum)
% of a band-limited signal from an irregular sampled timeseries using
% Adaptive weights, Conjugate gradients and Toeplitz matrices.
%
% Input:
%
% @var{xpn} : Vector -- sampling points in [0,(N-1)/N]
%
% @var{yp} : Vector -- corresponding sampling values
%
% @var{fmaxn} : Scalar -- maximum (band-limiting) frequency. Due to the
% scaling of @var{xpn} it has to be a positive integer.
%
% @var{itmax} : Scalar -- maximum number of reconstruction iterations.
% Default is twice the number of the frequencies.
%
% @var{thresh}: Scalar -- threshold for conjugate gradients (stop
% criterion). Default is machine precision.
%
% Output:
%
% @var{rfyp} : Columnvector -- reconstructed spectrum
%
% @var{err} : Columnvector -- error for each iteration step
%
% @emph{Note:}
%
% The use of this function requires normalized sampling points
% @var{xpn} in @code{[0,(N-1)/N]} and the knowledge of
% @var{fmaxn}. Use the function @code{irsa_normalize} for this task.
%
% @end deftypefn