version

ans =

    '9.5.0.944444 (R2018b)'

f1 ()

ans =

     0

f2 ()

ans =

     0

f3 ()
{Not enough input arguments.

Error in <a href="matlab:matlab.internal.language.introspective.errorDocCallback('sigma', '/home/michele/test-files/sigma.m', 2)" style="font-weight:bold">sigma</a> (<a href="matlab: opentoline('/home/michele/test-files/sigma.m',2,0)">line 2</a>)
  if (ischar (opt) && strcmp (opt, '-2'))

Error in <a href="matlab:matlab.internal.language.introspective.errorDocCallback('f3', '/home/michele/test-files/f3.m', 2)" style="font-weight:bold">f3</a> (<a href="matlab: opentoline('/home/michele/test-files/f3.m',2,0)">line 2</a>)
  r = eval ('sigma -2;');
} 
f3 (2)

ans =

     0

diary off