Re: What is f[1]? Advanced question

*To*: mathgroup at smc.vnet.net*Subject*: [mg131315] Re: What is f[1]? Advanced question*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Thu, 27 Jun 2013 06:32:35 -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

On 6/25/13 at 9:14 PM, Anthony.J.Mannucci at jpl.nasa.gov (amannucci) 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? x is a function that you have defined at specific values. Notice that In[1]:= x[1] = 0.1; x[2] = 0.2; x[3] = 0.3; In[4]:= DownValues[x] Out[4]= {HoldPattern[x(1)]:>0.1,HoldPattern[x(2)]:>0.2,HoldPattern[x(3)]:= >0.3} and In[5]:= f[y_] := y^2 In[6]:= DownValues[f] Out[6]= {HoldPattern[f(y_)]:>y^2} That is the values for x are stored exactly like the definition of an expression is what most think of as a function in Mathematica.