%metodo delle secanti

clear all
close all
clc

x=linspace(0.5,1.5);
f=@(x) 1./sqrt(x) -1;
Nmax=200;
tol=sqrt(eps);

[c] = SECANTI(f,x,Nmax,tol)
fplot(f)
xline(c)

function [x0] = SECANTI(f,x,Nmax,tol)
x0=x(1);
x1=x(end);
l=(x1-x0)/(f(x1)-f(x0));
x0= x1 - f(x0)/l;
k=1;
e(k)=abs(f(x0));

while k<Nmax && e(k)>tol

    temp=x0;
    x0= x0 - f(x0)/l;
    x1=temp;
    k=k+1;
    l = (f(x1) - f(x0))/(x1-x0);
    e(k)=abs(f(x0));

end

end