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I'm having trouble with setting up a particular range in a loop for my programming. Now I have a defined range of data (not continuous numbers) that needs to be applied in a loop. Since the aim for my code is to generate functions/expressions with the range automatically, I need to figure out a way to applied those data.

The code is

MapThread[(Subscript[C, #1][x, y] := 
     Subscript[q, 2 #1 - 1] + 
      x*Subscript[q, 2 #1] - (Subscript[q, #2] + 
        y*Subscript[q, #2 + 1])) &, {Range[], Range[]}];

data for #1 is: 3, 4, 5, 4, 6, 6, 6, 6. data for #2 is: 1, 2, 4, 3, 1, 2, 3, 5.

As u can see from the code, I cannot simply define the range in the loop. My idea is to create a list for the data and maybe apply it in the loop? thx for ur help!

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    $\begingroup$ 1) Please provide an equivalent code without Subscript (unless your question actually pertains to Subscript)... it only occludes your intent 2) Why haven't you inserted your "data" for #1 and #2 instead of Range[] (which does nothing, since it needs at least 1 arg) 3) Please edit your posts to make it proper English. We like to avoid "u", "thx", "ur", etc. and keep it clean. $\endgroup$
    – rm -rf
    Jan 15, 2014 at 3:01
  • $\begingroup$ If the OP could describe as precisely as possible what it is that he/she wants to do, rather than provide a vague explanation and non-functional code, then maybe it will be possible to help. $\endgroup$
    – heropup
    Jan 15, 2014 at 3:13
  • $\begingroup$ Also, you should note that since the list for #1 contains repeated elements you're just redefining Subscript[c, #1][x, y] n times, which I guess isn't what you're after $\endgroup$ Jan 15, 2014 at 3:18

1 Answer 1

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It looks like you are trying to define a collection of functions that are indexed by two variables #1 and #2. This code replaces #1 with i, #2 with j and defines all the functions within a Table.

Table[c[i_, j_, x_, y_] := q[2 j - 1] + x*q[2 i] - (q[j] + y*q[j + 1]), 
     {j, {1, 2, 4, 3, 1, 2, 3, 5}}, {i, {3, 4, 5, 4, 6, 6, 6, 6}}];

So now, for example, there are a collection of functions c indexed by the i and j, each defined in terms of x, y, and q[ ]. For example:

c[3, 4, x, y]
-q[4] - y q[5] + x q[6] + q[7]
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  • $\begingroup$ +1 for a great effort in trying to understand the question. But I haven't the slightest idea on how close you could be from the "real" question :) $\endgroup$ Jan 15, 2014 at 4:21
  • $\begingroup$ @belisarius I guess I was hoping to prompt "but that's not what I meant" from the OP so we could figure it out... it seemed like an interesting mix of naivete (such as malformed Range[ ] comamnds) and sophistication (such as MapThread). $\endgroup$
    – bill s
    Jan 15, 2014 at 4:25

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