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: spm_vb_init_block.m
    path of file: ./repos/bspm/thirdparty/spm12
    
    the code of the file until where you have to start completion: function [block] = spm_vb_init_block(Y,block)
% Initialise Variational Bayes for GLM-AR models
% FORMAT [block] = spm_vb_init_block(Y,block)
%
% Y      - [T x N] time series with T time points, N voxels
% block  - data structure (see spm_vb_glmar)
%__________________________________________________________________________
% Copyright (C) 2005-2014 Wellcome Trust Centre for Neuroimaging

% Will Penny and Nelson Trujillo-Barreto
% $Id: spm_vb_init_block.m 6079 2014-06-30 18:25:37Z spm $

k = block.k;
p = block.p;
N = block.N;
T = block.T;
X = block.X;


    
function [block] = spm_vb_init_block(Y,block)
% Initialise Variational Bayes for GLM-AR models
% FORMAT [block] = spm_vb_init_block(Y,block)
%
% Y      - [T x N] time series with T time points, N voxels
% block  - data structure (see spm_vb_glmar)
%__________________________________________________________________________
% Copyright (C) 2005-2014 Wellcome Trust Centre for Neuroimaging

% Will Penny and Nelson Trujillo-Barreto
% $Id: spm_vb_init_block.m 6079 2014-06-30 18:25:37Z spm $

k = block.k;
p = block.p;
N = block.N;
T = block.T;
X = block.X;

% Default optimisation parameters
if ~isfield(block,'tol')
    block.tol = 0.0001;
end