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Re: take square of the second and third column of a table

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124191] Re: take square of the second and third column of a table
  • From: Barrie Stokes <Barrie.Stokes at newcastle.edu.au>
  • Date: Thu, 12 Jan 2012 04:20:01 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201201112220.RAA22144@smc.vnet.net>

Hi

I like to use code that I think is explicit, i.e., I can see what I was doing when I read my code in 6 months time.

A = {{a, b, c}, {d, e, f}, {g, h, i}, {j, k, l}}

A // Column

B = Table[{A[[n]][[1]], A[[n]][[2]]^2, A[[n]][[3]]^2}, {n, 1, 4}]

Map[ (s \[Function] {
\!\(\*SubscriptBox[\(s\), \(\(\[LeftDoubleBracket]\)\(1\)\(\ \)\(\
\[RightDoubleBracket]\)\)]\), 
\!\(\*SubscriptBox[\(s\), \(\(\[LeftDoubleBracket]\)\(\ \)\(2\)\(\ \)\
\(\[RightDoubleBracket]\)\)]\)^2, 
\!\(\*SubscriptBox[\(s\), \(\(\[LeftDoubleBracket]\)\(\ \)\(3\)\(\ \)\
\(\[RightDoubleBracket]\)\)]\)^2}), A ]

Barrie

PS
Always a bad idea to use capitals for or as the first character of your variables; try C = 34.




>>> On 12/01/2012 at 9:20 am, in message <201201112220.RAA22144 at smc.vnet.net>,
hanciong awesome <hanciong at gmail.com> wrote:
> Hello, suppose I have a very long table like this:
> 
> 1 2 3
> 4 5 6
> 7 8 9
> .......
> 2 3 4
> 
> how can I take square of the 2nd and 3rd column? I always do it by
> making a new table. so let's say the above table is A and it has 100
> lines, then I make the new table as the following:
> 
> B=Table[{A[[n]][[1]],A[[n]][[2]]^2,A[[n]][[3]]^2},{n,1,100}]
> 
> But if the length of the table is unknown, this way is impractical.
> Could anyone suggests better way? thank you




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