title: Square root symbol label in Matlab
body: <p>How to get the square root sign inside a legend?
  I tried \surd, but did not consider all my expression below this symbol.
  \sqrt and \square do not work at all.</p>
  
  <pre><code>m=[2 4.8 7 9.1 11.5 15 20 29 59 90 130 190 250];
  size(Te);
  s=0:0.02:0.246;
  size(s);
  E0=0.1;
  t0=0.05;
  f=0.01;
  I0=2e9;
  I1=1e14.*[m./(3680.*(1.08)^(1./3))].^(1.5);
  hold on
  Ifitting=I0./(sqrt(2.*pi).*f).*exp(-[s-t0].^2./(2.*f.^2));
  [ay,h1,h2]=plotyy(s.*1e6,I1,s.*1e6,Ifitting,'loglog','plot')
  axes(ay(1)); ylabel(' Intensity');
  axes(ay(2)); ylabel('Intensity [fitting]');
  set(ay(1),'Ylim',[0 2e12])
  set(ay(2),'Ylim',[0 2e12])
  xlabel('time [\mu m]','FontSize',16,'FontName','Times-Roman');
  set([h1],'marker','o')
  set([h2],'marker','o')
  b=legend([h1 h2], ['I=10^{14}'],['I_{fitting}=I_0$$\sqrt{(2)\sigma}$$e^{\sigma}']);  
  set(b,'Interpreter','latex','fontsize',24)
  </code></pre>