Fzero returns non-zero value

Hello

I have a problem with the function fzero. The function returns a value of lambdastar where my function dphidlambda (see below) is far from zero (on the order of -100 to -200).

lambdastar=fzero(@(lambda) dphidlambda(lambda,q0,langd,Amax,Mmax,rho,lower_asym,alfa,nelem),[1e-9 1e9])

Does anyone know how to solve this problem? The strange thing is that fzero doesn't return any error message that it can't find any zero-point of the function dphidlambda.

\Jonas

[Walter Roberson]

I think you missed including the code for your function ?

[Matt Tearle]

And the output from fzero

Answer 1

[Matt Fig]

Include all the details, meaning: the function DPHIDLAMBDA, and the parameters used to call FZERO (q0,langd, Amax, etc).

If you include enough so that we can duplicate your results, then perhaps we could assist you in figuring out what went wrong.

Answer 2

[the cyclist]

Others are correct that more detail would help a lot in diagnosing, but I'll take a wild stab and suggest that you need to set something with tolerances. I suggest:

 >> doc optimset