function [r,sequence_x,sequence_fx]=secant(f,x_0,x_1,n_max,secant_tolerance)
% function [r,sequence_x,sequence_fx]=secant(f,x_0,x_1,n_max,secant_tolerance)
% runs the secant method starting with two points, 
% x_0 and x_1, to find a zero r of the function f with the tolerance 
% secant_tolerance in n_max steps, whichever is reached first. 
% It returns the zero r, and the sequence of approximations 
% sequence_x as well as the function values at these points sequence_fx
% The first two values of sequence_x are x_0 and x_1. 

%Your text of the secant function goes here.