use f=@(x) as an argument of a function.m

Question

DDD 2015-3-13

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/182977-use-f-x-as-an-argument-of-a-function-m

回答： Matt J 2015-3-13

I have the function

    function [ k ] = New_Raph( f,df,x,tol)
    x_old =x;
    x=1000;
    while abs(x_old-x) > tol
        x_old = x;
        delta=-f(x)/df(x);
        x= x-delta;
    end
    k=x;
    end

And i want to calculate in a new .m file:

    f=@(x) x.^5-0.4475.*x.^4-3.1.*x.^3+3.085.*x.^2-0.962.*x+0.0943;
    df1=@(x) 5.*x.^4-1.79.*x.^3-9.3.*x^2+6.17.*x-0.962;
    New_Raph(@f1,@df1,0,0.1)

What is wrong?

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Answer 1

per isakson 2015-3-13

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/182977-use-f-x-as-an-argument-of-a-function-m#answer_171202

编辑：per isakson 2015-3-13

在 MATLAB Online 中打开

Replace

New_Raph(@f1,@df1,0,0.1)

by

New_Raph(f,df1,0,0.1)

f or f1 - a typo?

&nbsp

Addendum triggered by &nbsp It did not work

Try this example

    >> my_sin = @(x) sin(x)
    my_sin = 
        @(x)sin(x)
    >> arrayfun( my_sin, pi/6*[1,2,3] )
    ans =
        0.5000    0.8660    1.0000
    >> arrayfun( @sin, pi/6*[1,2,3] )
    ans =
        0.5000    0.8660    1.0000

and

    >> arrayfun( @my_sin, pi/6*[1,2,3] )
    Error: "my_sin" was previously used as a variable, conflicting with its use 
    here as the name of a function or command.