how to get maximum value of this code

T = readtable('data1.xlsx') ; 
T = table2array(T) ;
x = T(1,2:end);  % coil length 
y = T(2:end,1);  % magnitude length
Z = T(2:end,2:end);  % use fillmissing to fill NaNs
[X,Y] = meshgrid(x,y) ;
[xq,yq] = meshgrid(2:0.1:10);     % grid interval 0.1
Zq = interp2(x,y,Z,xq,yq,'spline'); 

figure
AA = surf(xq,yq,Zq);
title('(spline,cubic,makima) Interpolation Using Finer Grid');

%%
% example
% if input (1, 1), in interpolation (2.0, 2.0)
% if input (23, 23) , in interpolation (42, 42)
% if input (81, 81) , in interpolation (10.0 , 10.0)
%  Upper limit& Lower limit are 1~81
Zq(1,1)
Zq(23,23)
Zq(81,81)

%% optimmization algorithm
% source : https://sites.google.com/a/hydroteq.com/www/


clc
% HS: Harmony Search minimization

% Use the Matlab startup random number sequence:
rand('twister',5489);   % Commment out to start rand from current position

% Specify objective function and bounds
f = Zq;
xL = [0.01 0.01]; % minimum range
xU = [0.81 0.81]; % maximum range

% Set HS algorithm parameters
HSparams.HMS = 10;
HSparams.MaxImp = 10000;
HSparams.HMCR = 0.8;
HSparams.PAR = 0.4;
HSparams.b = (xU-xL)/1000;

% Perform minimization
[xbest,fbest] = harmony(f,xL,xU,HSparams);
fprintf('Best solution found:\n')
disp(xbest)
fprintf('Function value = %f\n', fbest)

I want to find maxinmum of attached table. But when I use this code I get the minimum.

What should I fix to get the maximum value?

Answer 1

[Star Strider]

Important parts of the code appear to be missing.

However to get the maximum, negate the function —

f = @(x) sin(x);

x0 = rand;
[minimum,fvmin] = fminsearch(f, x0)

minimum = -1.5708

fvmin = -1.0000

[maximum,fvmax] = fminsearch(@(x)-f(x), x0)

maximum = 1.5708

fvmax = -1.0000

figure
plot((-pi:0.1:pi), sin((-pi:0.1:pi)))
hold on
plot(minimum,f(minimum),'vr',  maximum,f(maximum),'^r')
hold off
legend('Function','Minimum','Maximum', 'Location','best')
ylim(ylim*1.1)

.

[kyungdoo lee]

Is there any way to get the maximum value by modifying the code I posted?

[Star Strider]

Probably not because I have no idea what the objective is, what function is being used for the optimisation, and not unless the ‘Harmony’ function (and everything else necessary to run the code) appears!

[kyungdoo lee]

Thank you for answer

[Star Strider]

As always, my pleasure!

.