Re: Problem with Limit

*To*: mathgroup at smc.vnet.net*Subject*: [mg66859] Re: [mg66805] Problem with Limit*From*: gardyloo <gardyloo at mail.wsu.edu>*Date*: Thu, 1 Jun 2006 06:56:01 -0400 (EDT)*References*: <200605311030.GAA13862@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

I've plotted the function "t" as defined below (at least I think I've correctly changed all of the squares correctly) as a function of "g", for some arbitrarily chosen values of the parameters m1, k, and m2, and it appears that the limit of zero as g->0 is incorrect. C.O. Tony Harker wrote: > Can anybody explain why, for > > t =Sqrt[(k*m1 + k*m2 + m1*g + m2*g - > (1/2)*Sqrt[4*(m1 + m2)^2*(k + g)^2 - 16*k*m1*m2*(k + 2*g)])/ > (m1*m2)]/(1 + (k*m1 - k*m2 + m1*g - m2*g + > (1/2)*Sqrt[4*(m1 + m2)^2*(k + g)^2 - 16*k*m1*m2*(k + 2*g)])^2/ > (4*m1*m2*g^2)) + Sqrt[(k*m1 + k*m2 + m1*g + m2*g + > (1/2)*Sqrt[4*(m1 + m2)^2*(k + g)^2 - 16*k*m1*m2*(k + 2*g)])/ > (m1*m2)]/(1 + ((-k)*m1 + k*m2 - m1*g + m2*g + > (1/2)*Sqrt[4*(m1 + m2)^2*(k + g)^2 - 16*k*m1*m2*(k + 2*g)])^2/ > (4*m1*m2*g^2)); > > Limit[t, g -> 0] > Limit[Together[t], g -> 0] > > both give zero, whereas > > Limit[Simplify[Together[t]], g -> 0] > > gives a non-zero result? This is with Mathe4matica 5.2. > > > Dr A.H. Harker > Department of Physics and Astronomy > University College London > Gower Street > London > WC1E 6BT > > > > -- ========================================================== Curtis Osterhoudt PGP Key ID: 0x088E6D7A Please avoid sending me Word or PowerPoint attachments See http://www.gnu.org/philosophy/no-word-attachments.html ==========================================================