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

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

[Image Analyst]

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!

Answer 1

[Image Analyst]

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

[Ehi Eromosele]

would the correct method of defining f be?

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

before plotting...

[Image Analyst]

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