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: boxc_trans.m
    path of file: ./repos/malini/Codes/FC_EC_calculation code/DynamicFC/jplv7/regress
    
    the code of the file until where you have to start completion: function bdata = boxc_trans(x,lam)
% PURPOSE: compute box-cox transformation
%----------------------------------------------------
% USAGE: bdata = boxc_trans(data,lam)
% where:    lam  = scalar transformation parameter
%           data = matrix nobs x k
%----------------------------------------------------
% RETURNS: bdata = data matrix box-cox transformed

% written by:
% James P. LeSage, Dept of Economics
% University of Toledo
% 2801 W. Bancroft St,

    
function bdata = boxc_trans(x,lam)
% PURPOSE: compute box-cox transformation
%----------------------------------------------------
% USAGE: bdata = boxc_trans(data,lam)
% where:    lam  = scalar transformation parameter
%           data = matrix nobs x k
%----------------------------------------------------
% RETURNS: bdata = data matrix box-cox transformed

% written by:
% James P. LeSage, Dept of Economics
% University of Toledo
% 2801 W. Bancroft St,
% Toledo, OH 43606
% jlesage@spatial-econometrics.com
 
[n k] = size(x);
z = zeros(n,k);
iota = ones(n,1);

 for i=1:k;
   if lam ~= 0
   z(:,i) = (x(:,i).^lam - iota)/lam;
   else
   z(:,i) = log(abs(x(:,i)));
   end