Re: how to make Sum[n,{n,1,5}] to print 1+2+3+4+5? HoldForm?
- To: mathgroup at smc.vnet.net
- Subject: [mg79384] Re: how to make Sum[n,{n,1,5}] to print 1+2+3+4+5? HoldForm?
- From: Albert <awnl at arcor.net>
- Date: Wed, 25 Jul 2007 05:31:23 -0400 (EDT)
- References: <f86qdq$o7p$1@smc.vnet.net>
Nasser Abbasi wrote: > hi, I am using version 6 > > what is the trick to make Sum[] just print the terms first, before > adding them? Say I want to do > > r= Sum[n,{n,1,5}] > > But I want to see 1+2+3+4+5, i.e. the terms printed out before they > are actually added. > > then later I can do Evaluate[r] or N[r] something like this to get it > to actually do the sum. > > I tried the different Hold commands, but non seems to do it. the following does what I think you want, but it's somewhat verbose: In[17]:= r=Sum[With[{n=n},HoldForm[n]],{n,1,5}] Out[17]= 1+2+3+4+5 In[18]:= ReleaseHold[r] Out[18]= 15 the trick is to put the n into HoldForm in an evaluated form. hth, albert