You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: get_reg_filter.m
    path of file: ./repos/ECO/implementation/initialization
    
    the code of the file until where you have to start completion: function reg_filter = get_reg_filter(sz, target_sz, params, reg_window_edge)

% Compute the spatial regularization function and derive the corresponding
% filter operation used for the optimization

    
function reg_filter = get_reg_filter(sz, target_sz, params, reg_window_edge)

% Compute the spatial regularization function and derive the corresponding
% filter operation used for the optimization

if nargin < 3 || isempty(reg_window_edge)
    reg_window_edge = params.reg_window_edge;
end