function [r,iter] = secant(f,p0,p1,tol,nmax)
% by Shelvean Kapita
p = zeros(1,nmax);
p(1) = p0;
p(2) = p1;
i = 2;
res = 1;
while (res>tol)&&(i < nmax)
    p(i+1) = p(i)-f(p(i))*(p(i-1)-p(i))/(f(p(i-1))-f(p(i)));
    res = abs(p(i+1)-p(i));
    i = i+1;
end
r = p(1:i);
iter = i;