What is f[1]? Advanced question

*To*: mathgroup at smc.vnet.net*Subject*: [mg131300] What is f[1]? Advanced question*From*: amannucci <Anthony.J.Mannucci at jpl.nasa.gov>*Date*: Tue, 25 Jun 2013 21:14:08 -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

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 the answer is just what I have written above. Mathematica knows about x[1], x[2], etc. How does Mathematica know about the "elements" of x? In some other sense, I could have written: y1 = 0.1 y2 = 0.2 y3 = 0.3 But ?y obviously gives a different result (just returns y). Thank you.

**Follow-Ups**:**Re: What is f[1]? Advanced question***From:*"Louis Talman" <talmanl@gmail.com>

**Re: What is f[1]? Advanced question***From:*Bob Hanlon <hanlonr357@gmail.com>

**Re: What is f[1]? Advanced question***From:*Tomas Garza <tgarza10@msn.com>