hi , i'm trying to implement lagrange interpolation with the following code and it seems i'm failing, i tried to debug it but my patience has run out. have a go please and give me ideeas on how to make it do what it's supposed to do. i've read http://mathworld.wolfram.com/LagrangeInterpolatingPolynomial.html this and wrote the code. 

use strict;
use warnings;
use Math::Polynomial;
use Data::Dumper;


#points to interpolate tghrough
#(x,y)
my @points = @ARGV;
my @pair_points;



#the followin line is only for debugging
@points = ( 1,3,5,9,20,30) ;


while ( scalar @points ) {
    push @pair_points , [ pop @points , pop @points ];
}





sub P_j {
    my $n  =  scalar @points / 2;
    my $j = shift;
    my $pol = Math::Polynomial->new(1);
    $pol *= $pair_points[$j]->[1];
    for( my $k = 0 ; $k < $n ; $k++ ) {
        my $generic_pol =    Math::Polynomial->new( 1, -$pair_points[$
+k]->[0] ) /
                            ( $pair_points[$j]->[0] - $pair_points[$k]
+->[0])
                            unless $k == $j;
        $pol *= $generic_pol;
    }
    return $pol;
}



print P_j 4;

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In reply to lagrange interpolation by spx2

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