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Re^3: A script with a loop is running my computer Out of memory

by jdporter (Paladin)
on Feb 03, 2011 at 15:48 UTC ( [id://886011]=note: print w/replies, xml ) Need Help??


in reply to Re^2: A script with a loop is running my computer Out of memory
in thread A script with a loop is running my computer Out of memory

Look, if you know the generational growth rate (i.e. for each person in generation N, there are 2.5 people in generation N+1, or whatever), then just start with your 250 billion and work backwards. (2.5 is the average of rand(6).) 


$n = 250_000_000_000;

$a = 2.5;

while ($n>2) {
  print "$n\n";
  $n /= $a;
}

^D
250000000000
100000000000
40000000000
16000000000
6400000000
2560000000
1024000000
409600000
163840000
65536000
26214400
10485760
4194304
1677721.6
671088.64
268435.456
107374.1824
42949.67296
17179.869184
6871.9476736
2748.77906944
1099.511627776
439.8046511104
175.92186044416
70.368744177664
28.1474976710656
11.2589990684262
4.5035996273705

[download]

There. 28 generations.

Approximately.

Replies are listed 'Best First'.
Re^4: A script with a loop is running my computer Out of memory
by GrandFather (Saint) on Feb 03, 2011 at 19:49 UTC

    Or by modifying the compound interest formula to kill off the previous generation:

    use strict;
use warnings;

my $startPop = 4;
my $targetPop = 250e9;
my $increase = 2.5;
my $n = int ((log($targetPop) - log($startPop)) / log($increase) + 0.5
+);
my $pop = int ($startPop * ($increase) ** $n);

print "$pop population after $n generations\n";

    [download]

    Prints:

    222044604925 population after 27 generations

    [download]

    Add 1 instead of 0.5 in the $n calculation if you want a minimum of $targetPop.

    True laziness is hard work
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