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: BL_SVD.m
    path of file: ./repos/lrslibrary/libs/SVD
    
    the code of the file until where you have to start completion: function [U,S,V]=BL_SVD(A,u0,v0,k)

% Block lanczos method to compute SVD of matrix A with k steps; 
% Suppose A is m*n, where m>n; A0=U0*S0*V0', where U0 is m*r, V0 is n*r;
% This is equivalent to compute block lanczos on C=[0,A;A',0];
% The initial lanczos block should set to be uv0=[U0;V0]/sqrt(2);
% where r is the rank of A0 and c is the slack positive interger variable;
%
% A - m * n matrix (required input)
% [u0; v0]/sqrt(2) - Initial subspace (required input)
% k - the number of blocks
%
% U S V - partial singular value decomposition

    
function [U,S,V]=BL_SVD(A,u0,v0,k)

% Block lanczos method to compute SVD of matrix A with k steps; 
% Suppose A is m*n, where m>n; A0=U0*S0*V0', where U0 is m*r, V0 is n*r;
% This is equivalent to compute block lanczos on C=[0,A;A',0];
% The initial lanczos block should set to be uv0=[U0;V0]/sqrt(2);
% where r is the rank of A0 and c is the slack positive interger variable;
%
% A - m * n matrix (required input)
% [u0; v0]/sqrt(2) - Initial subspace (required input)
% k - the number of blocks
%
% U S V - partial singular value decomposition
%
% Reference: Zhouchen Lin and Siming Wei, A Block Lanczos with Warm Start 
% Technique for Accelerating Nuclear Norm Minimization Algorithms, 
% arxiv: 1012.0365.
%
% Bug report: zclin2000@hotmail.com
%

if nargin < 3
    error('Too few arguments') ;
end