Analysis by SBC

392

Name	신병춘

Subject	bisect_exa1.m

% bisect_exa1.m
% Find a root for f(x) = x^6-x-1
%
function [c,err]=bisect_exa1(a,b,tol,maxitr)
% Define a function
f = @(x) x.^6-x-1;
% Default tol=10^(-6), maxitr=100
if nargin==2, tol=10^(-6); maxitr=100; end
if f(a)*f(b)>0
    disp('f(a) and f(b) have same sign! Stop!'); return
elseif f(a)==0
    disp('a is a root!'); c = a; err = 0; return
elseif f(b)==0
    disp('b is a root!'); c = b; err = 0; return
end
fprintf('-------------------------------------------------------------------- \n')
fprintf('  n        a            b            c         |b-c|         f(c)  \n')
fprintf('-------------------------------------------------------------------- \n')
n = 1; c = (a+b)/2; err = abs(b-c); fc = f(c);
fprintf('%3.0f %12.8f %12.8f %12.8f %12.4e %12.4e \n',n,a,b,c,err,fc)
%
while (err>tol & n<=maxitr)
    if sign(f(b))*sign(f(c))==0
        disp('c is a root! Stop!'); return
    elseif sign(f(b))*sign(f(c))>0
        b = c;
    else
        a = c;
    end
    n = n+1; c = (a+b)/2; err = abs(b-c); fc = f(c);
    fprintf('%3.0f %12.8f %12.8f %12.8f %12.4e %12.4e \n',n,a,b,c,err,fc)
end

DATE: 2013.04.03 - 16:48

Newton method

Taylor_sin.m