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: test_roots.m
    path of file: ./repos/chebfun/tests/chebfun
    
    the code of the file until where you have to start completion: function pass = test_roots(pref)

if ( nargin == 0 )
    pref = chebfunpref();
end

%%

% Test a Sine function:
M = 1000;
f = chebfun(@(x) sin(M*pi*x), [0 1], pref);
exact = linspace(0, 1, M+1).';
r = roots(f);
pass(1) = length(r) == M+1 && norm(exact-r, inf) < 1e2*eps;


% Test a polynomial:
p = chebfun( '(x-.1).*(x+.9).*x.*(x-.9) + 1e-14*x.^5' );
e
    
function on [0, 100]:
f = chebfun(@(x) besselj(0,x), [0 100]);
r = roots(f);
exact = [ 2.40482555769577276862163; 5.52007811028631064959660
8.65372791291101221695437; 11.7915344390142816137431
14.9309177084877859477626; 18.0710639679109225431479
21.2116366298792589590784; 24.3524715307493027370579
27.4934791320402547958773; 30.6346064684319751175496
33.7758202135735686842385; 36.9170983536640439797695
40.0584257646282392947993; 43.1997917131767303575241
46.3411883716618140186858; 49.4826098973978171736028
52.6240518411149960292513; 55.7655107550199793116835
58.9069839260809421328344; 62.0484691902271698828525
65.1899648002068604406360; 68.3314693298567982709923
71.4729816035937328250631; 74.6145006437018378838205
77.7560256303880550377394; 80.8975558711376278637723
84.0390907769381901578795; 87.1806298436411536512617
90.3221726372104800557177; 93.4637187819447741711905
96.6052679509962687781216; 99.7468198586805964702799
];
pass(7) = length(r) == 32 && norm(exact - r, inf) < 1e2*hscale(f)*eps;


%%

% Test roots of a complex array-valued CHEBFUN:
f = chebfun(@(x) [1i*x, x, sin(2*pi*x)]);
exact = [[0,0;NaN(4,2)], linspace(-1,1,5).'];
r = roots(f);
pass(8) = all(size(exact) == [5,3]) && max(abs(exact(:) - r(:))) < 1e2*eps;

% Test roots of a complex quasimatrix:
f = quasimatrix(@(x) [1i*x, x, sin(2*pi*x)]);
exact = [[0,0;NaN(4,2)], linspace(-1,1,5).'];
r = roots(f);
pass(9) = all(size(exact) == [5,3]) && max(abs(exact(:) - r(:))) < 1e2*eps;

%% Test on singular function: piecewise smooth chebfun - splitting on.

% Set the domain
dom = [-2 7];

pow = -0.5;
op = @(x) (x-dom(1)).^pow.*cos(30*x);
f = chebfun(op, dom, 'exps', [pow 0], 'splitting', 'on');
r = roots(f);
r_exact = (((-19:66)+1/2)*pi/30).';
err = r - r_exact;
pass(10) = (norm(err, inf) < 1e2*get(f, 'vscale')*eps);


%% Tests for functions defined on unbounded domain:

% Functions on [-inf inf]:

% Set the domain:
dom = [-Inf Inf];

op = @(x) (1-exp(-x.^2))./x;
f = chebfun(op, dom);
r = roots(f);
r = r( isfinite(r) );
rExact = 0;
err = r - rExact;
pass(11) = norm(err, inf) < 1e2*eps*vscale(f);


% Blow-up function:
op = @(x) x.^2.*(1-exp(-x.^2))-2;
f = chebfun(op, dom, 'exps', [2 2]);
r = roots(f);
rExact = [-1.4962104914103104707 ; 1.4962104914103104707];
err = r - rExact;
pass(12) = norm(err, inf) < 1e2*eps*vscale(f);

% Functions on [a inf]:
dom = [0 Inf];

op = @(x) 0.15+sin(10*x)./exp(x);
f = chebfun(op, dom);
r = roots(f);
rExact = [0.33529141416564289113; 
          0.60061694515161002799;
          0.98375750309184861332;
          1.2042605667187311146;
          1.6619482204330474390;
          1.7760894757659030239];
err = r - rExact;
pass(13) = norm(err, inf) < 1e2*eps*vscale(f);


%% Test sale invariance (#911)

f = chebfun('exp(x)'); 
r = roots(f-1);
pass(14) = abs(r - eps) < 10*eps;
f = chebfun('exp(1e-50*x)',[-1e50 1e50]);
r = roots(f-1);
pass(15) = abs(r - 1e50*eps) < 1e51*eps;

f = chebfun('exp(1e50*x)',[-1e-50 1e-50]); 
r = roots(f-1);
pass(16) = abs(r - 1e-50*eps) < 1e-49*eps;


%% Test roots with periodic option

f = chebfun('cos(5*x).*exp(cos(x))',[-pi,pi],'periodic');
r = roots(f);
rExact = (-9:2:9)'*pi/10;
err = r - rExact;
pass(17) = norm(err, inf) < 1e2*eps*vscale(f);


f = chebfun('1i+cos(5*x).*exp(cos(x))',[-pi,pi],'periodic');
r = roots(f);
pass(18) = isempty(r);

% Check that we don't miss roots for unresolved functions.  (See GitHub issue
% #1146.)
warnState = warning('off', 'CHEBFUN:CHEBFUN:constructor:funNotResolved');
p = pref;
p.splitting = true;
p.splitPrefs.splitMaxLength = 300;
f = chebfun(@(x) sin(exp(2*(tanh(sin(10*x))))), [0 10], p);
pass(19) = length(roots(f)) == 32;
warning(warnState);

end