RootSearch issue

*To*: mathgroup at smc.vnet.net*Subject*: [mg112694] RootSearch issue*From*: "becko" <becko565 at hotmail.com>*Date*: Mon, 27 Sep 2010 05:47:03 -0400 (EDT)

Hi. This is an strange issue I'm having with v1.4 of Ersek's RootSearch package. I'm looking for the roots of a function and it so happens that if I specify a small interval, it finds the roots, but when I increase the interval, it doesn't find any root!. Specifically, here's a code sample: In[39]:= \[Gamma]even[r_, k_, e_] := I MathieuCPrime[MathieuCharacteristicA[r, k^2/4], k^2/4, I ArcTanh[Sqrt[1 - e^2]]]; rootsEven[r_, e_, {kmin_, kmax_}, opts : OptionsPattern[]] := RootSearch[\[Gamma]even[r, k, e] == 0, {k, kmin, kmax}, opts] // Quiet In[38]:= rootsEven[4, 5/20, {0, 10}][[All, 1, 2]] Out[38]= {1.35064, 2.3571, 3.21912} In[36]:= rootsEven[4, 5/20, {0, 100}][[All, 1, 2]] Out[36]= {1.35064, 2.3571, 3.21912} In[35]:= rootsEven[4, 5/20, {0, 1000}][[All, 1, 2]] Out[35]= {} Is there an explanation for this? Thanks.