#!/usr/bin/perl
use warnings;
use strict;

#3_3.pl
#loop over drop radius from 1 micron to 100 microns in steps of 2 micr
+ons
#use each radius to compute cross section
#if radius <20 microns, use (pi)*(r^2)*a*(1-exp(-c*r))
#if radius >= 20 microns, use 2*pi*(r^2)


my @radii = grep $_ & 1, 1 .. 100;

my $pi    = atan2 0, -1;
my $twopi = 2 * $pi;
my $a0    = 1.18;
my $c0    = 0.28e6;


my ( @rads, @sigs );

foreach my $r ( @radii ) 
    {
    push @rads, 1e-6 * $r;
#   push @sigs, $r > 20 ? $twopi * $rad ** 2 : $pi * $rad ** 2 * $a0 *
+ ( 1 - exp -$c0 * $rad );
# **Update: Oops, changed $rad to $rads[-1]
    push @sigs, $r > 20 ? $twopi * $rads[-1] ** 2 : $pi * $rads[-1] **
+ 2 * $a0 * ( 1 - exp -$c0 * $rads[-1] );
    }
    
print "@rads\n";
print "@sigs\n";
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