This is for two variable optimization problem using conjugate gradient method but I need to modify the provided code below so that I can check any function having more than two variable lets say 5 variables. Please help me I am new in matlab.

Question

SAKSHAM SHRIVASTAVA 2021-4-15

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/803141-this-is-for-two-variable-optimization-problem-using-conjugate-gradient-method-but-i-need-to-modify

回答： Alan Weiss 2021-4-16

clc

clear

format long

% Function Definition (Enter your Function here):

syms X Y;

f = -X - Y + 0.5*X^2 + X*Y + Y^2;

% Initial Guess:

x(1) = 0;

y(1) = 0;

e = 10^(-8); % Convergence Criteria

i = 1; % Iteration Counter

% Gradient Computation:

df_dx = diff(f, X);

df_dy = diff(f, Y);

J = [subs(df_dx,[X,Y], [x(1),y(1)]) subs(df_dy, [X,Y], [x(1),y(1)])]; % Gradient

S = -(J); % Search Direction

% Minimization Condition:

while norm(S) > e

I = [x(i),y(i)]';

syms h; % Step size

g = subs(f, [X,Y], [x(i)+S(1)*h,y(i)+h*S(2)]);

dg_dh = diff(g,h);

h = solve(dg_dh, h); % Optimal Step Length

x(i+1) = I(1)+h*S(1); % New x value

y(i+1) = I(2)+h*S(2); % New y value

J_old = [subs(df_dx,[X,Y], [x(i),y(i)]) subs(df_dy, [X,Y], [x(i),y(i)])];

i = i+1;

J_new = [subs(df_dx,[X,Y], [x(i),y(i)]) subs(df_dy, [X,Y], [x(i),y(i)])]; % Updated Gradient

S = -(J_new)+((norm(J_new))^2/(norm(J_old))^2)*S; % New Search Direction

end

% Result Table:`

Iter = 1:i;

X_coordinate = x';

Y_coordinate = y';

Iterations = Iter';

T = table(Iterations,X_coordinate,Y_coordinate);

% Plots:

fcontour(f, 'Fill', 'On');

hold on;

plot(x,y,'*-r');

% Output:

fprintf('Initial Objective Function Value: %d\n\n',subs(f,[X,Y], [x(1),y(1)]));

if (norm(S) < e)

fprintf('Minimum succesfully obtained...\n\n');

end

fprintf('Number of Iterations for Convergence: %d\n\n', i);

fprintf('Point of Minima: [%d,%d]\n\n', x(i), y(i));

fprintf('Objective Function Minimum Value: %d\n\n', subs(f,[X,Y], [x(i),y(i)]));

disp(T)

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Answer 1

Alan Weiss 2021-4-16

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/803141-this-is-for-two-variable-optimization-problem-using-conjugate-gradient-method-but-i-need-to-modify#answer_676701

See my answer here:

https://www.mathworks.com/matlabcentral/answers/801106-someone-please-help-me-i-have-made-a-2-variable-code-for-optimization-i-want-code-for-n-no-of?s_tid=srchtitle

Is there something there that you don't understand? If so, ask a specific question.

Alan Weiss

MATLAB mathematical toolbox documentation

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This is for two variable optimization problem using conjugate gradient method but I need to modify the provided code below so that I can check any function having more than two variable lets say 5 variables. Please help me I am new in matlab.

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This is for two variable optimization problem using conjugate gradient method but I need to modify the provided code below so that I can check any function having more than two variable lets say 5 variables. Please help me I am new in matlab.

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