hs.m

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

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

%% Harmony Search Parameters

MaxIt = MaxIt;     % Maximum Number of Iterations
HMS = nPop;         % Harmony Memory Size
nNew = 5;        % Number of New Harmonies

HMCR = 0.9;       % Harmony Memory Consideration Rate
PAR = 0.1;        % Pitch Adjustment Rate
FW = 0.02*(VarMax-VarMin);    % Fret Width (Bandwidth)
FW_damp = 0.995;              % Fret Width Damp Ratio

%% Start

% Empty Harmony Structure
empty_harmony.Position = [];
empty_harmony.Cost = [];
% Initialize Harmony Memory
HM = repmat(empty_harmony, HMS, 1);
% Create Initial Harmonies
for i = 1:HMS
HM(i).Position = unifrnd(VarMin, VarMax, VarSize);
HM(i).Cost = CostFunction(HM(i).Position);
end
% Sort Harmony Memory
[~, SortOrder] = sort([HM.Cost]);
HM = HM(SortOrder);
% Update Best Solution Ever Found
BestSol = HM(1);
% Array to Hold Best Cost Values
BestCost = zeros(MaxIt, 1);

%% Harmony Search Body

for it = 1:MaxIt
% Initialize Array for New Harmonies
NEW = repmat(empty_harmony, nNew, 1);
% Create New Harmonies
for k = 1:nNew
% Create New Harmony Position
NEW(k).Position = unifrnd(VarMin, VarMax, VarSize);
for j = 1:nVar
if rand <= HMCR
% Use Harmony Memory
i = randi([1 HMS]);
NEW(k).Position(j) = HM(i).Position(j);
end
% Pitch Adjustment
if rand <= PAR
%DELTA = FW*unifrnd(-1, +1);    % Uniform
DELTA = FW*randn();            % Gaussian (Normal) 
NEW(k).Position(j) = NEW(k).Position(j)+DELTA;
end
end
% Apply Variable Limits
NEW(k).Position = max(NEW(k).Position, VarMin);
NEW(k).Position = min(NEW(k).Position, VarMax);
% Evaluation
NEW(k).Cost = CostFunction(NEW(k).Position);
end
% Merge Harmony Memory and New Harmonies
HM = [HM
NEW]; %#ok
% Sort Harmony Memory
[~, SortOrder] = sort([HM.Cost]);
HM = HM(SortOrder);
% Truncate Extra Harmonies
HM = HM(1:HMS);
% Update Best Solution Ever Found
BestSol = HM(1);
% Store Best Cost Ever Found
BestCost(it) = BestSol.Cost;
% Show Iteration Information
disp(['In Iteration ' num2str(it) ': HS Cost Is = ' num2str(BestCost(it))]);
% Damp Fret Width
FW = FW*FW_damp;
end

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