CODEWITHSUNDEEP
matlab
Jov
Jov

Reputation: 1

Optimisation using Golden Search Method with Matlab

% Power output
power_output = MF_t.*difference.*e;

% POWER OUTPUT OPTIMIZATION USING - GOLDEN SEARCH METHOD 
x_lower = 0.2;
x_upper = 1.4;
h = (x_upper - x_lower);
r = (sqrt(5) - 1)*0.5;
x2 = x_lower + (1+r)*h;
x3 = x_upper - (1+r)*h;

tol = 0.05;
count = 1;

while h>-tol
    f2 = -power_output(x2)
    f3 = -power_output(x3)
    if f3<f2
        x_lower = x2;
        x_upper = x_upper;
        h = (x_upper - x_lower);
        x2 = x3;
        x3 = x_upper - (1-r)*h;
    elseif f2<f3
        x_lower = x_lower;
        x_upper = x3;
        h = (x_upper - x_lower);
        x3 = x2;
        x2 = x_lower + (1-r)*h;
    else
        x_lower = x2;
        x_upper = x3;
        h = (x_upper - x_lower);
        x2 = x_lower + (1+r)*h;
        x3 = x_upper - (1+r)*h;  
    end
    interval = x_upper - x_lower;
    count = count + 1
    if count > 100
        break
    end
end

answer = (x_upper + x_lower)/2
value = fanswer

Im trying to run this code, it's telling me that there is an error as my arrays f2 and f3 as "Array indices must be positive integers or logical values". I'm wondering would anyone know if taking the absolute values of my arrays will make my optimisation incorrect

Upvotes: 0

Views: 1015

Answers (1)

RPM
RPM

Reputation: 1769

The error message is quite informative in this case. You are trying to access the x2th element of f2. A quick calculation shows that on the first iteration x2 = 2.14. It is not possible to take the 2.14th element of f2 because this is is not an integer, and taking the absolute value will not help.

x2 is not an index, it is a value. On each iteration, the Golden Ratio search requires you to actually evaluate power_output with whatever variable set to x2. So, it looks like you need to do this calculation power_output = MF_t.*difference.*e with x=x2.

Upvotes: 1

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