# Newton's method

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Kevser Cifci on 12 Sep 2021
Commented: Kevser Cifci on 12 Sep 2021
Hello, I have to write a simple Newton function but it's not working:
%%file newton.m
function out = newton (f, df, x, eps)
k = 0;
h = f(x)/df(x); % error
while abs(h)>= eps && (k < 1000)
h = f(x)/df(x);
x = x - h;
k = k+1;
end
out = x;
end
Then I have to create a matrix which stocks the solutions of the newton's function and create a graph from this matrix but it's not working either:
%%file f1.m
function [out] = f1(x)
out = x.^3 - (6*x.^2)+ 11*x - 6;
end
%%file df1.m
function out=df1(x)
out=3*x.^2 - 12*x + 11;
end
Tab[]
for i = -1:0.05:5 %% I have to apply Newton on the values x = [-1:0.05:5]
Tab = [Tab [newton(i,f1,df1,10^(-8))]] %% error message: the variable Tab appears to change size on every loop iteration
end
plot(-1:0.05:5,Tab)

Matt J on 12 Sep 2021
Edited: Matt J on 12 Sep 2021
Tab=[];
for x = -1:0.05:5
Tab = [Tab , newton(@f1,@df1,x,10^(-8)) ]
end
Kevser Cifci on 12 Sep 2021

R2019a

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