my @radsigma;
for ( my $i=1; $i<=100; $i+=2 ) {
    my $sig;
    if ( $r <2 e-5 ) {
        $sig = sigmalow($r);
    }else{
        $sig = sigmahigh($r);
    }
    push @radsigma, [ $r, $sig ];
}

##</code><code>##

use strict;
use warnings;
use constant PI => 3.1416;

##</code><code>##

sub sigmalow {
    my $rad = shift;   # shift it off the front of @_
    my $rad = $_[0];   # or explicitly assign the value

##</code><code>##

for my $i (1..100){
    next unless $r % 2;

for (0..49){
    my $i = $_ * 2 + 1;

for my $i ( grep {$_ %2} (0..99 ) ){