www.gusucode.com > 高等数学问题求解源码程序 > CH07/bisect_demo.m
figure('Name','二分法几何意义','NumberTitle','off') f=@(x)exp(x)-x-5;a=1;b=4; [x,fx,iter,X]=bisect(f,a,b); ezplot(f,[a,b]+(b-a)*0.1*[-1,1]) hold on plot(xlim,[0 0],'r:',x,fx,'k*') Y=[a X(1:3) b];fY=f(Y); d=char('r','g','b'); plot([Y;Y],[fY;zeros(size(Y))],'k') for i=1:3 if f(X(i))*f(a)<0 xx=a+(X(i)-a)*[0 1/30 7/15 1/2 8/15 29/30 1]; plot([xx;xx+(X(i)-a)],[0 1 1 2 1 1 0]/80*diff(ylim)*(2.5-0.5*i)*(-1)^(i+1),d(i,:)) b=X(i); else xx= X(i)+(b-X(i))*[0 1/30 7/15 1/2 8/15 29/30 1]; plot([xx;xx+(X(i)-b)],[0 1 1 2 1 1 0]/80*diff(ylim)*(2.5-0.5*i)*(-1)^(i+1),d(i,:)) a=X(i); end end text(1.35,10,{'$$\Delta x = \frac{{b - a}}{2}$$'},'interpreter','latex','fontsize',14) text(1-0.1,1.5,'\fontname{times}\fontsize{16}\ita') text([2.5+0.05,4+0.05],[-1.5,-1.5],{'\itx','\itb'},'fontname','times','fontsize',16) text(1,60,'\fontname{隶书}\fontsize{16}二分法几何意义') text(3.5,50,'\fontname{times}\fontsize{16}{\ity}={\itf}({\itx})\rightarrow') xlabel('\itx','fontname','times','fontsize',16) ylabel('\ity','fontname','times','fontsize',16) title('') web -broswer http://www.ilovematlab.cn/forum-221-1.html