ch02.060_prob

Perl Best Practices the source code

##############################################################################
## Code fragment (NOT RECOMMENDED) from Chapter 2 of "Perl Best Practices"  ##
##     Copyright (c) O'Reilly & Associates, 2005. All Rights Reserved.      ##
##  See: http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html  ##
##############################################################################


# Standard modules...
use strict;
use warnings;
use IO::Prompt;
use Carp;
use English qw( -no_match_vars );
use Data::Alias;
use Readonly;


Readonly my $DRAG_COEFF => 0.000_001;

my @steps            = (0);
my $radial_velocity  = 10;
my $orbital_velocity = 100;
my $phase            = 0.1;
my $phase_shift      = 45;
my $altitude         = 100_000;

for my $elapsed_time (1..10) {
    add_step( \@steps, $steps[-1] 
                    + $radial_velocity * $elapsed_time 
                    + $orbital_velocity * ($phase + $phase_shift)
                    - $DRAG_COEFF * $altitude
                    , $elapsed_time);
}

sub add_step {
    my ($steps_ref, $next_step, $elapsed_time) = @_;
    push @{$steps_ref}, {$elapsed_time => $next_step};
}

use Data::Dumper 'Dumper';
warn Dumper [ @steps ];