makeTemporalFilters.m

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% Anne Urai and Klaus Wimmer, 2016
% anne.urai@gmail.com / kwimmer@clinic.ub.es

function [kernel1, kernel2, cfg] = makeTemporalFilters(cfg)

% set defaults
if ~isfield(cfg, 'k'),          cfg.k          = 60;              end
if ~isfield(cfg, 't_range'),    cfg.t_range    = [0 0.3];         end
if ~isfield(cfg, 'nslow'),      cfg.nslow      = 3;               end
if ~isfield(cfg, 'nfast'),      cfg.nfast      = 5;               end
if ~isfield(cfg, 'frameRate'),  error('frameRate required!');     end

% formula's from Kiani et al. 2008
g1 = @(t) (cfg.k*t).^cfg.nslow .* exp(-cfg.k*t) .* (1/factorial(cfg.nslow) - ((cfg.k*t).^2) / factorial(cfg.nslow + 2));
g2 = @(t) (cfg.k*t).^cfg.nfast .* exp(-cfg.k*t) .* (1/factorial(cfg.nfast) - ((cfg.k*t).^2) / factorial(cfg.nfast + 2));

% number of points for the kernel in t 
% (looks complicated but just ensures an odd number of points so that the center is at zero)
t_n = ceil((cfg.t_range(2) - cfg.t_range(1)) * cfg.frameRate);  
t   = linspace(cfg.t_range(1), cfg.t_range(2), t_n)';

% get the kernels
kernel1 = g1(t);
kernel2 = g2(t);

end