% -----------------------------------------------------------------------
% This file is part of the ASTRA Toolbox
% 
% Copyright: 2010-2018, iMinds-Vision Lab, University of Antwerp
%            2014-2018, CWI, Amsterdam
% License: Open Source under GPLv3
% Contact: astra@astra-toolbox.com
% Website: http://www.astra-toolbox.com/
% -----------------------------------------------------------------------

vol_geom = astra_create_vol_geom(256, 256);
proj_geom = astra_create_proj_geom('parallel', 1.0, 384, linspace2(0,pi,180));

% As before, create a sinogram from a phantom
P = phantom(256);
[sinogram_id, sinogram] = astra_create_sino_gpu(P, proj_geom, vol_geom);
figure(1); imshow(P, []);
figure(2); imshow(sinogram, []);

% Create a data object for the reconstruction
rec_id = astra_mex_data2d('create', '-vol', vol_geom);

% Set up the parameters for a reconstruction algorithm using the GPU
cfg = astra_struct('SIRT_CUDA');
cfg.ReconstructionDataId = rec_id;
cfg.ProjectionDataId = sinogram_id;

% Create the algorithm object from the configuration structure
alg_id = astra_mex_algorithm('create', cfg);

% Run 1500 iterations of the algorithm one at a time, keeping track of errors
nIters = 1500;
phantom_error = zeros(1, nIters);
residual_error = zeros(1, nIters);
for i = 1:nIters;
  % Run a single iteration
  astra_mex_algorithm('iterate', alg_id, 1);

  residual_error(i) = astra_mex_algorithm('get_res_norm', alg_id);
  rec = astra_mex_data2d('get', rec_id);
  phantom_error(i) = sqrt(sumsqr(rec - P));
end

% Get the result
rec = astra_mex_data2d('get', rec_id);
figure(3); imshow(rec, []);

figure(4); plot(residual_error)
figure(5); plot(phantom_error)

% Clean up.
astra_mex_algorithm('delete', alg_id);
astra_mex_data2d('delete', rec_id);
astra_mex_data2d('delete', sinogram_id);