Re: Using "Sum" (i = 1 ... N) in a function definition
- To: mathgroup at smc.vnet.net
- Subject: [mg49701] Re: [mg49666] Using "Sum" (i = 1 ... N) in a function definition
- From: János <janos.lobb at yale.edu>
- Date: Thu, 29 Jul 2004 07:43:12 -0400 (EDT)
- References: <200407271100.HAA11129@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
I would start with a fresh Mathematica session, or Clear all the variables... On my machine - G4 OSX 10.3.4 and Mathematica 5.0.1 your code is working fine. dlist = {a, b, c, d, e, f, g, h} dfunc[i_] := Sum[Part[dlist, j], {j, 1, i}] dfunc[5] a + b + c + d + e János On Jul 27, 2004, at 7:00 AM, Rainer wrote: > I was trying to define a function using the Sum command in the > following way (simplified example): > > MyData = {3,2,4,5,6}; > MyFunc[i_] = Sum[MyData[[j]],{j,1,i}]; > > As you can see, the idea is to use the length of the list (i) > as a variable in the function definition, such that > > MyFunc[1] = 3 > MyFunc[2] = 3 + 2 = 5 > MyFunc[3] = 3 + 2 + 4 = 9 > > etc. Mathematica does not like the abobe statements, and prints the > following error message: > > "Part specification K$394 is neither an integer nor a list of > integers." > > Does anybody know how to define (correctly) such a function. Should be > possible ...? > Thanks > Rainer > > --------- "During my service in the United States Congress, I took the initiative in creating the Internet." -- Al Gore "If Al Gore invented the internet, I invented spell check." -- Dan Quayle --- borrowed from Deirdre Saoirse * http://www.linuxcabal.org * http://www.deirdre.net
- References:
- Using "Sum" (i = 1 ... N) in a function definition
- From: wilhelm.rainer@gmx.net (Rainer)
- Using "Sum" (i = 1 ... N) in a function definition