Re: Plotting a function -

*To*: mathgroup at smc.vnet.net*Subject*: [mg71666] Re: Plotting a function -*From*: Bill Rowe <readnewsciv at sbcglobal.net>*Date*: Sun, 26 Nov 2006 03:48:49 -0500 (EST)

On 11/25/06 at 5:37 AM, tharkun860 at publicspam.com (Craig Reed) wrote: >Hi - > >I'm trying to get Mathematica 5.2 to graph a function which is the >ratio of integers which have a '3' in them. Done in Exce3l, the >graph of the first 32,000 data points has a fractal look to it, >especially when done with a log scale. >What I've tried is the following >f[x_] := Boole[DigitCount[x, 10, 3]] >g[x_] := Sum[f, {i, x}]/x >Plot[g, {x, 1, 100}] >I get 3 errors of "g is not a michine-size real number at" followed >by 3 real numbers: 1.000004125 5.016125..... 9.39607..... >What am I doing wrong? or perhaps what I should ask is, "Is there a >better way?" You have a variety of errors in your code that are causing the problem. You have defined the functions f and g to have an argument. Yet when you call the function you don't supply an argument. That is g needs to be defined as follows: g[x_]:=Sum[f[i],{i,x}]/x Similarly when you plot g the syntax is Plot[g[x],{x,1,100}] But you also have a problem with your definition of f. The argument to Boole needs to be an expression not an integer that will be returned by DigitCount. That is you need something like f[x_]:=Boole[DigitCount[x,10,3]>0] -- To reply via email subtract one hundred and four