function [xvect,xdif,fx,nit] = secant(x1,x0,nmax,fun,toll);% SECANT   Do the secant iteration to find the zeros of the given% inline scalar function and its derivative. %    [XVEC,XDIF,FX,NIT] = SECANT(X1,X0,NMAX,FUN,TOLL)  %       Input:x0 and x1 starting value%             nmax: maximum number of iteration%             toll: tolerance, default is 1e-10%             fun: given inline function%%      Output: xvect: stores values in all iterations (arg)%              xdif : difference between two successive values%              (arg) %              fx: stores function values  in all iterations %              nit: number of iteration required%%     Examples:%          fun=inline('x^3+x^2-4'); x0=0.3;x1=0.5; nmax=100;%          fun=inline('x^5+10*x^2-9*x+10');% Author: Bishnu Lamichhane, University of Stuttgartif (nargin==4)  toll=1e-10; endx=x1;fx1=feval(fun,x);xvect=[x]; fx=[fx1]; x=x0; fx0=feval(fun,x); xvect=[xvect;x];fx=[fx;fx0];err=toll+1;nit=0;xdif=[]; while(nit<nmax & err>toll)   nit=nit+1;   if (abs(fx0-fx1)<eps)     err=toll*1e-10;     disp('Stop for vanishing dfun');   else     x=x0-fx0*(x0-x1)/(fx0-fx1);     xvect=[xvect;x];   fnew=feval(fun,x);   fx=[fx;fnew];   err=abs(x0-x);   xdif=[xdif;err];   x1=x0;fx1=fx0;x0=x;fx0=fnew;   end; end;n=1:nit;plot(n, xdif, '-*');title(['Plot of error with respect to iteration, f(x)=',char(fun)]);xc = get(gca,'XLim');yc = get(gca,'YLim');xc = (xc(1)+xc(2))/2;text(xc,yc(2)*0.9,['x_{zero} = ',num2str(x)], ...									 'HorizontalAlignment', 'center');