How to find out the separation between to peaks of the azimuthally polarised beam at full width at half maxiumu?

Hi, I have problem in the following code, can anyone help me in this regard, it is great help for me;

[kx,ky]=meshgrid(-1:2/31:1,-1:2/31:1); c=sqrt(kx.^2+ky.^2)<1; N.A=0.5; alp=asin(N.A); k0=1/sin(alp);

kz=sqrt(k0.^2-(kx.^2+ky.^2)); GX=sqrt(k0./kz).*((k0*ky.^2+kz.*kx.^2)./(k0*(kx.^2+ky.^2))); GY=sqrt(k0./kz).*((kz-k0).*kx.*ky)./(k0*(kx.^2+ky.^2)); GZ=-sqrt(k0./kz).*(kx/k0);

ph=(pi+atan2(kx,ky)); ph=rot90(ph,3).*c; la=-sin(ph).*c;

lb=rot90(cos(ph).*c,3); k=1024; Ex=(la.*GX.*c+rot90(-lb.*GY.*c,3)); FEx=fftshift(fft2(Ex,k,k)); Ix=FEx.*conj(FEx);

Ey=(la.*GY.*c+rot90(lb.*GX.*c,3)); FEy=fftshift(fft2(Ey,k,k)); Iy=FEy.*conj(FEy);

Ez=(la.*GZ.*c+rot90(lb.*GZ.*c,3)); FEz=fftshift(fft2(Ez,k,k)); Iz=FEz.*conj(FEz);

I=Ix+Iy; %figure(1) %imagesc(I),colormap gray;axis image; axis off; %figure(2) %plot(I(16,:)) %figure(3) %imagesc(Iz),colormap gray;axis image; axis off; %figure(4) %plot(Iz(16,:)) I1=Ix+Iy+Iz; I0=max(max(I1(k/2,:))); I1(k/2,:)=I1(k/2,:)/I0; a=max(max(I1(k/2,:))) %figure(5) %imagesc(I),colormap gray;axis image; axis off; figure(6) plot(I1(k/2,:))

If you run this program you find figure(6), from this figure I have to find out separation between two peaks at full width at half maximum

In advance thank you mohd abdul gaffar

[Oleg Komarov]

Please format the code http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup