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: icatb_iva_laplace.m
    path of file: ./repos/bspm/thirdparty/MIALAB/GroupICATv4.0a/icatb/icatb_analysis_functions/icatb_algorithms
    
    the code of the file until where you have to start completion: function [W,cost,isi] = icatb_iva_laplace(X,varargin)
% [W,cost,isi] = iva_laplace(X,varargin)
%
% Implementation of the independent vector analysis (IVA)
% al
    
function mag=vecmag(vec,varargin)
% mag=vecmag(vec)
% or
% mag=vecmag(v1,v2,...,vN)
%
% Computes the vector 2-norm or magnitude of vector. vec has size n by m
% represents m vectors of length n (i.e. m column-vectors). Routine avoids
% potential mis-use of norm built-in function. Routine is faster than
% calling sqrt(dot(vec,vec)) -- but equivalent.
if nargin==1
    mag=sqrt(sum(vec.*conj(vec)));
else
    mag=vec.*conj(vec);
    for ii=1:length(varargin)
        mag=mag+varargin{ii}.*conj(varargin{ii});
    end