Help with creating a Newton-Raphson algorithm function

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IKIK
IKIK 2018-11-17
编辑： madhan ravi 2018-11-17
As a part of a MATLAB course I've been asked to create a function that will solve a mathematical function by using Newton-Raphson algorithm.
So I've written the following function:
function s=newtRaph(Y,x1)
syms x
y=diff(Y,x);
Y=subs(Y,x,x1);y=subs(y,x,x1);
for i=1:4
xx=x1-(Y/y);
x1=xx;
end
s=x1;
And called it in the script like so:
syms x
y=x-cos(x);
newtRaph(y,3)
The problem is that i get the following ans instead of the solution:
ans =
(4*(cos(3) - 3))/(sin(3) + 1) + 3
Can anyone tell me what am I doing wrong?

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madhan ravi
madhan ravi 2018-11-17
Can anyone tell me what am I doing wrong?
Since you created a function with a single output you have to also call it with an output .
as below:
Solution=newtRaph(y,3)
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IKIK
IKIK 2018-11-17
编辑：IKIK 2018-11-17
or try this file exchange https://www.mathworks.com/matlabcentral/fileexchange/4313-newton-raphson?s_tid=answers_rc2-1_p4_MLT
Maybe that is the solution but it is way beyond my level of understanding.
Thank you for your help
madhan ravi
madhan ravi 2018-11-17
编辑：madhan ravi 2018-11-17
Anytime :) ,If it helped you make sure to accept the answer

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更多回答（1 个）

Greg Heath
Greg Heath 2018-11-17
编辑：Greg Heath 2018-11-17
Add the line
ans = ans
Hope this helps.
Thank you for formally accepting my answer
Greg

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