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Re: Function of list of functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg104090] Re: Function of list of functions
  • From: David Bailey <dave at removedbailey.co.uk>
  • Date: Mon, 19 Oct 2009 07:10:03 -0400 (EDT)
  • References: <hb9k72$rv$1@smc.vnet.net> <hbc8aj$ctt$1@smc.vnet.net> <hben5a$gud$1@smc.vnet.net>

Andrey wrote:
> On Oct 17, 3:03 pm, David Bailey <d... at removedbailey.co.uk> wrote:
>> Andrey wrote:
>>> Hello!
>>> May be anybody can help me. So, I have this:
>>> L = {{1, 2, 3}, {1, 2, 3}, {1, 2, 3}};
>>> Fun1[t_] := ListPlot[L[[1, t]]];
>>> Fun2[t_] := ListPlot[L[[2, t]]];
>>> Fun3[t_] := ListPlot[L[[3, t]]];
>>> FunRes[t_] := {Fun1[t], Fun2[t], Fun3[t]};
>>> Everything is ok, BUT if I want to add element to list of FunRes[t_]
>>> in loop, I have an error? so I mean this:
>>> FunRes[t_] := {};
>>> For[i = 1, i <= 3, i++,
>>>    {Subscript[Fun, i][t_] := ListPlot[L[[i, t]]],
>>>    AppendTo[FunRes[t], Subscript[Fun, i][t]]}]
>>> Please, help me, where I am wrong?
>> It is very hard to figure out what you want to achieve here. Here are a
>> few thoughts:
>>
>> Let's start with a list where we can tell what we are plotting:
>>
>> L = {{1, 2, 3}, {10, 20, 30}, {100, 200, 300}};
>>
>> This will plot the second sublist:
>>
>> ListPlot[L[[2]]]
>>
>> Here is a function that will plot the n'th sublist:
>>
>> fun[n_] := ListPlot[L[[n]]]
>>
>> e.g.
>>
>> fun[3]
>>
>> Note that in your code FunRes[t] evaluates a function, so it makes
>> absolutely no sense to use AppendTo on the result!
>>
>> Tell us what you really want to do, and someone will tell you how to do i=
> t!
>> BTW, it is highly recommended that you don't use variable names that
>> start with a capital letter (unless you use a special character further
>> in the name) to avoid confusion with Mathematica's symbols.
>>
>> David Baileyhttp://www.dbaileyconsultancy.co.uk
> 
> Thank you everybody for your replays. Sorry for my english. I wanted
> this, and it is works:
> 
> L = {{1, 2, 3}, {1, 2, 3}, {1, 2, 3}};
> 
> FuncTestList[n_, v_] := L [[n, v]]
> FunRes[v_] := Table[FuncTestList[i, v], {i, 1, 3}]
> 
> 
Well, using your definitions, I get

In[11]:= FunRes[2]

Out[11]= {2, 2, 2}

I honestly don't see what use this is!

Mathematica beginners usually get the most useful answers if they supply 
a little data (as you did), and then explain what sort of output they 
would like to obtain. I still don't understand what it is you really 
want to do!

I changed your test data for a reason - you really want all the integers 
in L to be different - otherwise you can't be sure what Mathematica has 
done!

David Bailey
http://www.dbaileyconsultancy.co.uk


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