function [x,ierr] = newton(f, fd, x0, epsi, delta, maxf, maxstep)
% Newton's method for evaluating a root of the function
% f whose derivative is given in fd.
%
% calling sequence: [x,ierr] = newton(@f, @fd, x0, epsi, delta, maxf, maxstep)
%
% f  = name of the matlab function that evaluates f
% fd = name of the matlab function that evaluates f'
% x0 = initial guess for the root x
% epsi = terminate (with ierr=0) if two successive x values 
%    differ by less than this amount
% delta  = terminate (with ierr=0) if |f| drops below this value
% maxf = maximum number of iterations; terminate with ierr=2 if exceeded
% maxstep = terminate (with ierr=1) if step is longer than this value
%
% the routine prints out iteration number, x, and f at each iteration
%