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: ft_scalpcurrentdensity.m
    path of file: ./repos/fieldtrip
    
    the code of the file until where you have to start completion: function [scd] = ft_scalpcurrentdensity(cfg, data)

% FT_SCALPCURRENTDENSITY computes an estimate of the SCD using the
% second-order derivative (the surface Laplacian) of the EEG potential
% distribution
%
% The relation between the surface Laplacian and the SCD is explained
% in more detail on http://tinyurl.com/ptovowl.
%
% Use as

    
function [scd] = ft_scalpcurrentdensity(cfg, data)

% FT_SCALPCURRENTDENSITY computes an estimate of the SCD using the
% second-order derivative (the surface Laplacian) of the EEG potential
% distribution
%
% The relation between the surface Laplacian and the SCD is explained
% in more detail on http://tinyurl.com/ptovowl.
%
% Use as
%   [data] = ft_scalpcurrentdensity(cfg, data)
% or
%   [timelock] = ft_scalpcurrentdensity(cfg, timelock)
% where the input data is obtained from FT_PREPROCESSING or from
% FT_TIMELOCKANALYSIS. The output data has the same format as the input
% and can be used in combination with most other FieldTrip functions
% such as FT_FREQANALYSIS or FT_TOPOPLOTER.
%
% The configuration should contain
%   cfg.method       = 'finite' for finite-difference method or
%                      'spline' for spherical spline method
%                      'hjorth' for Hjorth approximation method
%   cfg.elec         = structure with electrode positions or filename, see FT_READ_SENS
%   cfg.trials       = 'all' or a selection given as a 1xN vector (default = 'all')
%   cfg.feedback     = string, 'no', 'text', 'textbar', 'gui' (default = 'text')
%
% The finite method require the following
%   cfg.conductivity = conductivity of the scalp (default = 0.33 S/m)
%
% The spline and finite method require the following
%   cfg.conductivity = conductivity of the scalp (default = 0.33 S/m)
%   cfg.lambda       = regularization parameter (default = 1e-05)
%   cfg.order        = order of the splines (default = 4)
%   cfg.degree       = degree of legend