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: struct_normalize.m
    path of file: ./repos/imtsl/libs/tensorlab
    
    the code of the file until where you have to start completion: function [x,state] = struct_normalize(z,task)
%STRUCT_NORMALIZE Normalize columns to unit norm.
%   [x,state] = struct_normalize(z,[]) normalizes the columns of z so that
%   x(:,i) = z(:,i)/norm(z(:,i)) for all indices i. The structure state
%   stores information which is reused in computing the right and left

    
function [x,state] = struct_normalize(z,task)
%STRUCT_NORMALIZE Normalize columns to unit norm.
%   [x,state] = struct_normalize(z,[]) normalizes the columns of z so that
%   x(:,i) = z(:,i)/norm(z(:,i)) for all indices i. The structure state
%   stores information which is reused in computing the right and left
%   Jacobian-vector products.
%
%   struct_normalize(z,task) computes the right or left Jacobian-vector
%   product of this transformation, depend