fa.m

function [x,err,BestCost]=fa(CostFunction,nVar,MaxIt,nPop)

%% Variables 
VarSize = [1 nVar];   % Decision Variables Matrix Size
VarMin = -5;         % Decision Variables Lower Bound
VarMax = 5;         % Decision Variables Upper Bound

%% Firefly Algorithm Parameters

MaxIt = MaxIt;         % Maximum Number of Iterations
nPop = nPop;            % Number of Fireflies (Swarm Size)
gamma = 2;            % Light Absorption Coefficient
beta0 = 4;            % Attraction Coefficient Base Value
alpha = 0.2;          % Mutation Coefficient
alpha_damp = 0.98;    % Mutation Coefficient Damping Ratio
delta = 0.05*(VarMax-VarMin);     % Uniform Mutation Range
m = 2;
if isscalar(VarMin) && isscalar(VarMax)
dmax = (VarMax-VarMin)*sqrt(nVar);
else
dmax = norm(VarMax-VarMin);
end

%% Start

% Empty Firefly Structure
firefly.Position = [];
firefly.Cost = [];
% Initialize Population Array
pop = repmat(firefly, nPop, 1);
% Initialize Best Solution Ever Found
BestSol.Cost = inf;
% Create Initial Fireflies
for i = 1:nPop
pop(i).Position = unifrnd(VarMin, VarMax, VarSize);
pop(i).Cost = CostFunction(pop(i).Position);
if pop(i).Cost <= BestSol.Cost
BestSol = pop(i);
end
end
% Array to Hold Best Cost Values
BestCost = zeros(MaxIt, 1);

%% Firefly Algorithm Body

for it = 1:MaxIt
newpop = repmat(firefly, nPop, 1);
for i = 1:nPop
newpop(i).Cost = inf;
for j = 1:nPop
if pop(j).Cost < pop(i).Cost
rij = norm(pop(i).Position-pop(j).Position)/dmax;
beta = beta0*exp(-gamma*rij^m);
e = delta*unifrnd(-1, +1, VarSize);
newsol.Position = pop(i).Position ...
+ beta*rand(VarSize).*(pop(j).Position-pop(i).Position) ...
+ alpha*e;
newsol.Position = max(newsol.Position, VarMin);
newsol.Position = min(newsol.Position, VarMax);
newsol.Cost = CostFunction(newsol.Position);
if newsol.Cost <= newpop(i).Cost
newpop(i) = newsol;
if newpop(i).Cost <= BestSol.Cost
BestSol = newpop(i);
end
end
end
end
end
% Merge
pop = [pop
newpop];
% Sort
[~, SortOrder] = sort([pop.Cost]);
pop = pop(SortOrder);
% Truncate
pop = pop(1:nPop);
% Store Best Cost Ever Found
BestCost(it) = BestSol.Cost;
% Show Iteration Information
disp(['In Iteration ' num2str(it) ': FA Cost Is = ' num2str(BestCost(it))]);
% Damp Mutation Coefficient
alpha = alpha*alpha_damp;
end

x=BestSol.Position';
err=BestSol.Cost;