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MathGroup Archive 2013

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Re: List:{1}, {2,3},{4,5,6}....

  • To: mathgroup at smc.vnet.net
  • Subject: [mg129417] Re: List:{1}, {2,3},{4,5,6}....
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Fri, 11 Jan 2013 22:26:44 -0500 (EST)
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  • References: <20130111023936.D243068E0@smc.vnet.net>

m = 5;

t1 = Timing[
   list1 = Table[
      i + 1, {n, 1, m}, {i, n (n - 1)/2, n (n - 1)/2 + n - 1}];][[1]]

0.000083

t2 = Timing[
   list2 = Table[Range[n (n - 1)/2 + 1, n (n + 1)/2], {n, m}];][[1]]

0.000054

t1/t2

1.5

list1 == list2

True

m = 1000;

t3 = Timing[
   list3 = Table[
      i + 1, {n, 1, m}, {i, n (n - 1)/2, n (n - 1)/2 + n - 1}];][[1]]

0.368475

t4 = Timing[
   list4 = Table[Range[n (n - 1)/2 + 1, n (n + 1)/2], {n, m}];][[1]]

0.010008

t3/t4

36.82

list3 == list4

True


Bob Hanlon


On Thu, Jan 10, 2013 at 9:39 PM, hknetman <hknetman at hotmail.com> wrote:
> I use the command
> list = Table[i + 1, {n, 1, 5}, {i, n (n - 1)/2, n (n - 1)/2 + n - 1}]
> to get the following result:
> {{1}, {2, 3}, {4, 5, 6}, {7, 8, 9, 10}, {11, 12, 13, 14, 15}}
>
> Is there any better method?
>
> Thanks a lot.
>



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