fzero function not working for equation, says undefined for double

Question

Jessica Hainline 2022-3-4

回答： Walter Roberson 2022-3-4

Editor:

function f=HW6Q2(x)
f=3*cos(x^(1/5))-x^3;

Command Window:

>> x=fzero(@HW6Q2,1)

Error using fzero>localFirstFcnEval (line 729)

FZERO cannot continue because user-supplied function_handle ==> HW6Q2 failed with the error below.

Undefined function 'HW6Q2' for input arguments of type 'double'.

Error in fzero (line 286)

fx = localFirstFcnEval(FunFcn,FunFcnIn,x,varargin{:});

I have no idea why this is wrong. How do I get my function to handle a 'double'?

Answer 1

Walter Roberson 2022-3-4

x=fzero(@HW6Q2,1)
x = 1.1563
function f=HW6Q2(x)
    f=3*cos(x^(1/5))-x^3;
end

You must not have saved the code under the file name HW6Q2 somewhere on your MATLAB path.