You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: binfish.m
    path of file: ./repos/opt_matlab/第16章/例16.5
    
    the code of the file until where you have to start completion: function [best_x,fval]=binfish(fun,fishnum,LB,UB,nvar,max_iterm,visual,step,try_number,delta)   %人工鱼群算法求TSP,n为维数
esp1=1e-8;
if isempty(visual)

    
function [best_x,fval]=binfish(fun,fishnum,LB,UB,nvar,max_iterm,visual,step,try_number,delta)   %人工鱼群算法求TSP,n为维数
esp1=1e-8;
if isempty(visual)
    parameter.visual=ceil(unifrnd(nvar*0.4,nvar*0.6,1));
else
    parameter.visual=ceil(visual);
end