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.