convert this pseudo code to matlab

The pseudo code attached. There are some strange point in code that i dont understand. Especially in sigma adding. How can i use fi in sigma. All hitogram values or something. ANybody help me to convert this into matlab code in simple way. I start like this

Index E calculate before;
Ah=trapz(imhist(image);
gmin=min(image(:));
gmax=max(image(:));

but histogram F={fi} i dont understand and also step 2 how can i wr[i]te it or convert; thanks