Beginner--Error in Series expansion
- To: mathgroup at smc.vnet.net
- Subject: [mg68155] Beginner--Error in Series expansion
- From: abdou.oumaima at hotmail.com
- Date: Wed, 26 Jul 2006 02:26:19 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello mathgroup, When I'm trying to find a power series of this function, It doesn't yield the correct expression: Z[L_] = Sum[(((-1)^Lp/( L - Lp + 1))*(1/ksi^Lp)), {Lp, 0, L}] - (-1)^L Log[1 + ksi]/ksi^(L + 1) devZ[L_] = Normal[Series[Z[L], {ksi, 0, 2}]] devZ[3] I get: devZ[3]= 1/4 -1/ksi^3+1/2 ksi +(ksi-ksi^2/2)/ksi^4. This code must yield: devZ[3]= ksi/5 - ksi^2/6 +0(ksi^3) How to correct this error. Any help will be very welcome. Lian.