fwhm.m

求解ppln中脉冲传输的问题 采用split step fourier method

function y = fwhm1(t,u)
% Full-width Half Maximum

tlead = 0;   ttrail = 0;
lower = 0;   upper = 0;
nt = length(u);
M=1;
It1 = u;
n=1;while n<M+1;
   I1peak(n) = max(It1(n,:));
   m=2;while It1(n,m) < I1peak(n)/2;
      m=m+1;
   end
   lower = It1(n,m-1);upper=It1(n,m);
   tlead = t(m-1)*(upper-I1peak(n)/2)/(upper-lower)+t(m)*(I1peak(n)/2-lower)/(upper-lower);
   while It1(n,m) > I1peak(n)/2;
      m=m+1;
   end
   lower = It1(n,m-1);upper = It1(n,m);
   ttrail = t(m-1)*(upper-I1peak(n)/2)/(upper-lower)+t(m)*(I1peak(n)/2-lower)/(upper-lower);   
   fwhm1(n) = ttrail-tlead;
   n=n+1;
end
y = fwhm1(n-1);