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Why is there an error? Undefined function 'f' for input arguments of type 'double'.

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Ehi Eromosele 2014-3-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/120349-why-is-there-an-error-undefined-function-f-for-input-arguments-of-type-double

评论： Image Analyst 2014-3-5

采纳的回答： Image Analyst

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Error using arrayfun

Undefined function 'f' for input arguments of type 'double'.

Error in golden (line 3)

plot(t,arrayfun(@f,t));

function golden(a, b)

t=[a:0.01:b];

plot(t,arrayfun(@f,t));

hold on

tol=10^(-12);

r=(3-sqrt(5))/2;

c=a+r*(b-a);

d=b-r*(b-a);

fa=f(a);

fb=f(b);

fc=f(c);

fd=f(d);

while (b-a>tol)

    if (fc<fd)
        b=d;
        fb=fd;
        d=c;
        fd=fc;
        c=a+r*(b-a);
        fc=f(c);
        plot(c,fc,'r*');
    else
        a=c;
        fa=fc;
        c=d;
        fc=fd;
        d=b-r*(b-a);
        fd=f(d);
        plot(d,fd,'r*');
    end

end

fprintf('Minimum found at x=%.12f \n', (a+b)/2, f(a+b)/2);

hold off

end

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Image Analyst 2014-3-5

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup Don't double space. Just highlight then click {}Code. Don't click {}Code before highlighting either!

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采纳的回答

Image Analyst 2014-3-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/120349-why-is-there-an-error-undefined-function-f-for-input-arguments-of-type-double#answer_127221

Well, you did not define f, just like it said. What do you think f should be? You have to tell it!

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Ehi Eromosele 2014-3-5

would the correct method of defining f be?

f(x)=2*sin(ax)-sin(bx);

before plotting...

Image Analyst 2014-3-5

Look up "anonymous functions" then try it and see. That's the best way to learn.

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