I took a stab at it thinking that 's' was the sum and 'm' was the previous value for 'x'

I am pretty certain that this is incorrect.

#!/usr/bin/perl -w
use strict ;

my %epan ;
my @data ;
my $sum ;

while ( <STDIN> ) 
{
   my @line= split  ;
   push (@data,$line[0]) ;
}


#Epanechnikov: 0.75*(1-((x-m)/s)**2)/s if abs( (x-m)/s ) < 1, otherwis
+e 0
for ( my $i = 0 ; $i <= $#data ; $i++ )
{
   $sum+=$data[$i] ;
   if ($sum !=0 && abs(($data[$i]-$data[$i-1])/$sum) < 1)
   {   
      $epan{$i}=0.75*(1-(($data[$i]-$data[$i-1])/$sum)**2)/$sum ;
   } else {
      $epan{$i} = 0 ;
   }
}


for ( my $i = 0 ; $i <= $#data ; $i++ )
{
  print "$data[$i] $epan{$i}\n" ;
}
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