Re: What is f[1]? Advanced question

*To*: mathgroup at smc.vnet.net*Subject*: [mg131367] Re: What is f[1]? Advanced question*From*: Helen Read <readhpr at gmail.com>*Date*: Mon, 1 Jul 2013 05:51:38 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net*References*: <kqm704$hpb$1@smc.vnet.net>

x is not an array. It is a symbol which in this case has not been defined. It does not refer to the list. If you were to name the array, like this: b= Array[x, 3] The list is named b, and you can extract the entries with double brackets. b[[2]] Perhaps your confusion arises from the fact that b[[2]] and x[2] are equal. Here is another example that will perhaps clarify. c = Array[x, 5, -8] c[[1]] (* first entry of c. Not the same as x[1] *) c[[2]] (* second entry of c. Not the same as x[2] *) On 6/29/2013 4:48 AM, Tomas Garza wrote: > In[2]:= Array[x, 3] > > Out[2]= {x[1], x[2], x[3]} > > x is an array and is indexed with single brackets (cf. the Help browser). > -Tomas > >> From: talmanl at gmail.com >> Subject: Re: What is f[1]? Advanced question >> To: mathgroup at smc.vnet.net >> Date: Fri, 28 Jun 2013 04:15:13 -0400 >> >> On Tue, 25 Jun 2013 19:14:08 -0600, amannucci >> <Anthony.J.Mannucci at jpl.nasa.gov> wrote: >> >>> I have found a Mathematica program with the following construct: >>> x[1]=0.1 >>> x[2]=0.2 >>> x[3]=0.3 >>> or >>> Do[x[i]=i/10.,{i,1,3}] >>> x is not a function. It is not a list. What is it? If I query x thus: >>> ?x >> >> x most certainly *is* a function. Its a function whose domain contains >> just the three numbers 1, 2, and 3. >> >> And it is *not* an array. Mathematica has lists, which it uses as arrays >> on occasion. An array, y, is indexed with double brackets: a[[1]], >> a[[2]], etc. >> >> --Louis A. Talman >> Department of Mathematical and Computer Sciences >> Metropolitan State University of Denver >> >> <http://rowdy.msudenver.edu/~talmanl> > >