Having a slight problem with Newton-Raphson loop. No errors in command window..

Question

Kokalz 2012-10-15

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/50937-having-a-slight-problem-with-newton-raphson-loop-no-errors-in-command-window

采纳的回答： Matt Fig

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Hi everybody!

First, thank you very much for answering my previous question about the anonymous functions.

The new issue is:

I'm trying to make Matlab solve equations using Newton - Raphson method. So far I've written my code trying to follow the guide on youtube. The only problem is that the user there is using symbolic math toolbox, which I don't have. So I am trying to use the " Numerical differentiation " method and use anonymous function as an input.

Here is my code:

 function [root, iterations] = newtonRaphson(funIn, guessValue)
 x = guessValue;
 for u=0:2814 % max number of iterations
    y=x; 
    derivative = @(x) (funIn(x+0.001)-funIn(x))/0.001; % Numerical diff.
    x=y-funIn(x)/derivative(x);  % Newton-Raphson formula.
    if x==y
        root = x
        iterations = u
        break 
    end
 end

I then use " newtonRaphson(@(x) sin(x) - x, 10) " as an input. The function, unfortunately does nothing, the command window is absolutely empty and I don't even know what the error is. Any ideas guys?

Thank you very much for your help guys!