function sqroot(x)
% SQROOT Compute square root by Newton's method

% Check that value of function argument is positive.

  if x <= 0,
     error('In sqroot() : argument x must be positive');
  end;

% Initial guess

  xstart = x/2;

% Iteration loop to compute square root

  for i = 1:100
      xnew = ( xstart + x/xstart)/2;     % new estimate of square root.
      disp(xnew);                        % print xnew.
      if abs(xnew - xstart)/xnew < eps,  % check convergence of iterations.
         break,                          % iterations.
      end;
      xstart = xnew;                     % update estimate of square root.
  end