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Topic: help with fzero
Replies: 1   Last Post: Aug 3, 2008 11:55 PM

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ganesh

Posts: 37
Registered: 2/15/06
help with fzero
Posted: Aug 3, 2008 7:44 AM
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hi
i am trying to find roots of a characteristic equation (determinant of
matrix).
i know the interval within which the root lies.
but the characteristic equation also has singularities in that
interval.
when i try to find out roots of this equation with the function fzero
in matlab

>> x=fzero(@fun,0.080)

it returns with an error saying :

>> 'Exiting fzero: aborting search for an interval containing a sign change
because complex function value encountered during search.
(Function value at 0.0768 is -30.9664+1.77636e-015i.)
Check function or try again with a different starting value.'

>>


this happens after just two iterations.

i have following questions:
1) why matlab has problem with a complex valued function?

2) Since the function value has not reached zero yet, I still
need to
search for the root. How do i skip the values where function
becomes
singular (in this case Complex) ?

any help is greatly appreciated.




Date Subject Author
8/3/08
Read help with fzero
ganesh
8/3/08
Read Re: help with fzero
mike zander

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