newtraph.m

来自「several numerical method code」· M 代码 · 共 14 行

function[root,ea,iter]=newtraph(func,dfunc,xr,es,maxit,varargin)
if nargin<4||isempty(es),es=0.02;end
if nargin<5||isempty(maxit),maxit=50;end
iter=0;
while(1)
    xrold=xr;
    xr=xr-func(xr)/dfunc(xr);
    iter=iter+1;
    if xr~=0, ea=abs((xr-xrold)/xr)*100;end
    if ea<=es||iter>=maxit, break, end
    disp(' [r]     [xr]        [ea]');
    disp(sprintf(' %d     %d       %d\n',iter,xrold,ea))
end
root=xr;