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### Re: [OT] Normalizing the return result of an exponential formula

by kennethk (Abbot)
 on Apr 14, 2011 at 18:00 UTC ( #899499=note: print w/replies, xml ) Need Help??

Based on your post and discussion with BrowserUk, my first thought is a Gaussian - see Normal_distribution. The functional form gives you a width parameter and the normalization is known, so it will satisfy your importance and radius requirements. You could probably implement your boost parameter by modifying the exponent on x. Perhaps something like:
```#!/usr/bin/perl -w
use warnings;
use strict;

sub boost  {
my (\$x, \$importance, \$radius, \$drop) = @_;

return \$importance * exp( -(\$x/\$radius)**\$drop );
}

my \$imp  = 1000;
my \$drop = 1;

for (map 2**\$_, 1..15) {
my \$boost = boost(\$_, \$imp, \$rad, \$drop);
my \$bar = "@" x (\$boost/\$imp*50);
printf "%6d %s %.1f\n", \$_, \$bar, \$boost;
}
__END__
2 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 980.2
4 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 960.8
8 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 923.1
16 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 852.1
32 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 726.1
64 @@@@@@@@@@@@@@@@@@@@@@@@@@ 527.3
128 @@@@@@@@@@@@@ 278.0
256 @@@ 77.3
512  6.0
1024  0.0
2048  0.0
4096  0.0
8192  0.0
16384  0.0
32768  0.0

Update: Fixed typo in call order.

Replies are listed 'Best First'.
Re^2: [OT] Normalizing the return result of an exponential formula
by clinton (Priest) on Apr 14, 2011 at 18:09 UTC
kennethk that looks like just the ticket! Many thanks

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 [marioroy]: Is List::Util::XS a core Perl module? [stevieb]: corelist List::Util::XS says "List::Util::XS was first released with perl v5.10.1" [stevieb]: so yes, since v5.10.1 :) [MidLifeXis]: According to [metaperl:// corelist], Perl 5.10.1 Lady_Aleena blurbles. One of her favorite modiles is now in "maintenance mode" in favor of a new fangled module. [MidLifeXis]: D'oh. Slow out of the gate. [marioroy]: Thanks stevieb, MidLifeXis. [MidLifeXis]: corelist Typo. Wow. Time to go, fingers are malfunctioning. [marioroy]: Thanks MidLifeXis. Leaned another thing about Perl. Wow.

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