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: cf.m
    path of file: ./repos/chebfun/@chebfun
    
    the code of the file until where you have to start completion: function [p, q, r, s] = cf(f, m, n, M)
%CF   Caratheodory-Fejer approximation
%   [P, Q, R_HANDLE] = CF(F, M, N) computes a type (M,
    
function [s, u, k, l, rFlag] = getBlock(a, m, n, M)
% Each Hankel matrix corresponds to one diagonal m - n = const in the CF-table;
% when a diagonal intersects a square block, the eigenvalues on the
% intersection are all equal.  k and l tell you how many entries on the
% intersection appear before and after the eigenvalues under consideration.  u
% is the corresponding eigenvector

tol = 1e-14;

if ( n > M + m + 1 )
    c = zeros(1, n - m - M - 1);
    nn = M + m + 1;
else
    c = [];
    nn = n;
end