二分法求方程的零解
function bisect0=bisect(xl,xu,es)clc
clear all
fun=inline('sin(10*x)+cos(3*x)','x'); XL=3;Xu=5;
max_iter=50;es=0.001; iter=1;
XX=possible_root(fun,XL,Xu,0.1)
m_root=size(XX,1);
for number=1:m_root
xl=XX(number,1);xu=XX(number,2);
fl=fun(xl);xr=xl;
while iter<max_iter
xrold=xr;
xr=(xl+xu)/2;
fr=fun(xr);
if xr~=0 % 计算相对误差
ea=abs((xr-xrold)/xr)*100;
end
%%%%%%%%%%%%%%%%%%%%%区间变换%%%%%%%%%%%
test=fl*fr;
if test<0
xu=xr;
elseif test>0
xl=xr;
fl=fr;
else ea=0;
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
if ea<es
break;
end
bisect(number,:)=xr;
iter=iter+1;
end
end
bisect=bisect
error=fun(bisect)
end
function xr=possible_root(fun,xl,xu,size)
n=xl:size:xu;m=1;
for cnt=1:length(n)-1;
test=fun(n(cnt))*fun(n(cnt+1));
if test<0
xr1(m,:)=;
m=m+1;
end
end
xr=xr1;
end
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