function [p1,err,k,y]=secant(f,p0,p1,delta,epsilon,max1)%Input - f is the object function input as a string 'f'%      - p0 and p1 are the initial approximations to a zero of f        %	    - delta is the tolerance for p1%	    - epsilon is the tolerance for the function values y%	    - max1 is the maximum number of iterations%Output - p1 is the secant method approximation to the zero%	     - err is the error estimate for p1%	     - k is the number of iterations%	     - y is the function value f(p1)%  NUMERICAL METHODS: Matlab Programs% (c) 2004 by John H. Mathews and Kurtis D. Fink%  Complementary Software to accompany the textbook:%  NUMERICAL METHODS: Using Matlab, Fourth Edition%  ISBN: 0-13-065248-2%  Prentice-Hall Pub. Inc.%  One Lake Street%  Upper Saddle River, NJ 07458for k=1:max1		p2=p1-feval(f,p1)*(p1-p0)/(feval(f,p1)-feval(f,p0));		err=abs(p2-p1);	relerr=2*err/(abs(p2)+delta);	p0=p1;	p1=p2;	y=feval(f,p1);	if (err<delta)|(relerr<delta)|(abs(y)<epsilon),break,endend