[wenroutianshi]

非常感谢上面的两位，我仔细看了一下是while 后面没加括号。大家再帮我看一下这个程序为什么还是出执行while循环体呢，
clc
clear
a0=0.2
b0=1
a1=a0
a3=b0
a2=0.6
c1=(fun2(a3)-fun2(a1))/(a3-a1)
c2=((fun2(a2)-fun2(a1))/(a2-a1)-c1)/(a2-a3)
a=1/2*(a1+a3-c1/c2)
while (abs(a-a2))>0.01
if a>a2
if fun2(a)<fun2(a2)
a3=a
else
a1=a2
a2=a
end
else
if fun2(a)<fun2(a2)
a3=a2
a2=a
else
a1=a
end
end
c1=(fun2(a3)-fun2(a1))/(a3-a1)
c2=((fun2(a2)-fun2(a1))/(a2-a1)-c1)/(a2-a3)
a=1/2*(a1+a3-c1/c2)
end
x=a
函数体是：
function y=fun2(x)
y=x+20/x