Re: "Help please: Summing a list"

*To*: mathgroup at smc.vnet.net*Subject*: [mg13510] Re: "Help please: Summing a list"*From*: erra at esiea.fr (ERRA Robert)*Date*: Fri, 31 Jul 1998 04:33:25 -0400*Organization*: The Math Forum*References*: <6pebm8$i6j@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hello Rob, in place of PP[[i]]:=Sum[P[[n]],{n,0,i}]; use the following definition: PP[i_]:=Sum[P[[n]],{n,1,i}]; (*1*) or, if you really want to use the function PP with only integer arguments, you can use PP[i_Integer]:=Sum[P[[n]],{n,1,i}]; (*2) but in your case this is not a problem to use (*1*). Take a look about definition of a function to understand the use of i_ in place of i in the definition. A Mathematica list begins always with the indice 1, if you ask P[[0]] you will have the Head of P, i.e. In[3]:=P[[0]] gives Out[3]:=List Have a look at FullForm[P] to see why. A bientôt, Robert Erra.