bisection method - can't see error in code

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Christie
Christie 2012-10-3
I am unable to pin point the error in my code of my funtion for the bisection method, any help would be greatly appreciated
function [rootx]=bisect(fhandle,a,b,epsilon)
rootx=[];
Fa=fhandle(a);
Fb=fhandle(b);
m=((b-a)/2);
Fm=fhandle(m);
while abs(m)>epsilon ;
if Fb*Fm <0
a=m
else
b=m
end
end
return m=((a+b)/2)
end
rootx

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采纳的回答

James Tursa
James Tursa 2012-10-3
1) Google "bisection method"
2) Go to the 1st Wiki link
3) Look at the pseudo-code posted there
4) Compare that to your code to discover your errors, paying special attention to what Matt J said about not updating your variables within your loop.

更多回答（2 个）

Matt J
Matt J 2012-10-3
编辑：Matt J 2012-10-3
One idea:
m=((b-a)/2);
Shouldn't it be + instead of - ?
Also, you don't assign anything to rootx in the code except the initialization rootx=[]. Also, throughout the loop, you are not updating, m, Fb, or Fm.
Babak
Babak 2012-10-3
In the while loop
while abs(m)>epsilon ;
if Fb*Fm <0
a=m
else
b=m
end
end
you are not changing m and you are trying to check the abs(m)
I think you meant
m=a
and
m=b
instead...

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