       Re: fastest way to add up a billion numbers

• To: mathgroup at smc.vnet.net
• Subject: [mg73907] Re: fastest way to add up a billion numbers
• From: "dimitris" <dimmechan at yahoo.com>
• Date: Sat, 3 Mar 2007 00:55:02 -0500 (EST)
• References: <es92b2\$3oj\$1@smc.vnet.net>

```There is recent post of mine asking something relevant here.

You can find also a relevant thread here:

http://forums.wolfram.com/mathgroup/archive/2005/May/msg00600.html

One billion numbers?
Here is what I get to my PC

In:=
Range[10^9]
>From In:=
No more memory available.
Mathematica kernel has shut down.
Try quitting other applications and then retry.

In:=
Table[i, {i, 1, 10^9}];

>From In:=
No more memory available.
Mathematica kernel has shut down.
Try quitting other applications and then retry.

Anyway...

lst = Range[10^6];

Timing[Plus @@ lst]
{0.34299999999999997*Second, 500000500000}

Timing[Total[lst]]
{0.2659999999999999*Second, 500000500000}

Timing[Fold[Plus, 0, lst]]
{0.703*Second, 500000500000}

Timing[lst /. {x_, y___} -> x + y]
{0.45300000000000007*Second, 500000500000}

Timing[Tr[lst]]
{0.3899999999999997*Second, 500000500000}

Timing[Sum[lst[[i]], {i, 1, 10^6}]]
{1.4379999999999997*Second, 500000500000}

But for your case I should simply suggest

Timing[Sum[i,{i,1,10^9}]]
{0.047 Second,500000000500000000}

Regards
Dimitris

=CF/=C7 Raj =DD=E3=F1=E1=F8=E5:
> hi!
>
> Could somebody tell me what would be the fastest way to add up a
> billion numbers(from 1 to 10^9 i.e the first billion numbers) in
> Mathematica?
>
> Ofcourse the answer is n(n+1)/2, but is there any other way in
> Mathematica other than the following one:
>
> Total@@Range[10^9]
>
> Thanks,
>
> Raj

```

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