chord.m

various matlab programs to slove various problems

function [xvect,xdif,fx,nit]=chord(a,b,x0,nmax,toll,fun)
x=a; 
fa=eval(fun); 
x=b; 
fb=eval(fun); 
r=(fb-fa)/(b-a);
err=toll+1; 
nit=0; 
xvect=x0; 
x=x0; 
fx=eval(fun); 
xdif=[];
while (nit < nmax & err > toll)
    nit=nit+1; 
    x=xvect(nit); 
    xn=x-fx(nit)/r; 
    err=abs(xn-x); 
    xdif=[xdif; err]; 
    x=xn; 
    xvect=[xvect;x]; 
    fx=[fx;eval(fun)];
end
return