% Secant method looks for a zero of function f using an
% iterative method, with first guess x=a, b.  It stops when |f(x_n)| < tol. 
% it returns the root and the iterates (x). 
%
% function [root,x] = secant(a,b,tol)

function [root,x] = secant(a,b,tol)

test = abs(f(a));
i = 1;
x0 = a;
x1 = b;
x(i) = x1; 
while test > tol
  x_new = x1-f(x1)*(x1-x0)/(f(x1)-f(x0));
  x0 = 	x1;
  x1 = x_new;
  test = abs(f(x_new));
  i = i+1;
  x(i) = x_new;
end

root = x_new;