problem with passing a function handle to a function

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Diego Soler Polo 2016-4-21

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https://ww2.mathworks.cn/matlabcentral/answers/280211-problem-with-passing-a-function-handle-to-a-function

评论： Diego Soler Polo 2016-4-22

I have a code to implement Newton-Rapshon algorithm fo find the zeroes of a function. In order to try it, I defined in the terminal:

f=@(x)x^2-1
df=@(x)2*x

And then I call my function in the terminal like this: Newton1(f,df,10^-7,10,3). It should work just fine.... but instead it gives the error message: * "??? Undefined function or method 'Newton1' for input arguments of type 'function_handle'."*

I have no idea what's going wrong! Any help will be appreciated :-) The code I am using is as follows:

function [root] = Newton1(f,df,tolerance,Iterations,x0)   
epsilon = 10^(-14);          %Don't want to divide by a number smaller than this
%Iterations;          %Don't allow the iterations to continue indefinitely
haveWeFoundSolution = false; %Have not converged to a solution yet
for i = 1 : Iterations
      y = f(x0);
      yprime = df(x0);
      if abs(yprime) < epsilon                         %Don't want to divide by too small of a number
          % denominator is too small
          break                                        %Leave the loop
      end
      x1 = x0 - y/yprime;                                %Do Newton's computation
      if abs(x1 - x0) <=  tolerance * abs(x1)         %If the result is within the desired tolerance
          haveWeFoundSolution = true;
          break;                                        %Done, so leave the loop
      end
      x0 = x1;                                           %Update x0 to start the process again
end
if haveWeFoundSolution
    root=x0;
   %Sol=printf('%s is a root of the equation',x0);
   disp(root)
else
   display('The process did not converge')
end

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Steven Lord 2016-4-21

Or if you are using release R2010b or later and have the file open in the MATLAB Editor, right-click on the tab with its name and select the option to change directory to the folder containing that file. [This generally won't work for files whose names are "Untitled" followed by 0 or more numbers, as that naming convention usually indicates the file hasn't been saved yet.]

Diego Soler Polo 2016-4-22