5.4每日总结

今天学习了matlif，学会了其基本的使用

并且编写了一些程序，如下：

golds.m

function [xmin, fmin, iter] = golds(fun, a, b, tol)

rho = (sqrt(5) - 1) / 2;

x1 = a + (1 - rho) * (b - a);

x2 = a + rho * (b - a);

f1 = fun(x1);

f2 = fun(x2);

iter = [a, b, x1, x2; zeros(floor(log2((b - a) / tol)), 4)];

for k = 1:size(iter, 1) - 1

    if f1 < f2

        b = x2;

        x2 = x1;

        x1 = a + (1 - rho) * (b - a);

        f2 = f1;

        f1 = fun(x1);

    else

        a = x1;

        x1 = x2;

        x2 = a + rho * (b - a);

        f1 = f2;

        f2 = fun(x2);

    end

    iter(k + 1, :) = [a, b, x1, x2];

    if abs(b - a) < tol

        break;

    end

end

if f1 < f2

    xmin = x1;

    fmin = f1;

else

    xmin = x2;

    fmin = f2;

end

iter = iter(1:k + 1, :);

untitled2.m

[umin, fmin, iter] = golds(@(x) x^2 - sin(x), 0, pi, 1e-6);

disp(['极小点 = ' num2str(umin)]);

disp(['极小值 = ' num2str(fmin)]);

disp(iter);