my $val = $my_pdl->index($i);

##</code><code>##

my $val = $my_pdl->at($i);

##</code><code>##

#!/usr/bin/env perl

use strict;
use warnings;

use PDL;
use Benchmark qw(:all);

cmpthese(
    100,
    {   'pdl_values'  => sub {&pdl_value},
        'perl_values' => sub {&perl_scalar_value},
    }
);

exit;

sub pdl_value {
    my $pdl = ones( float, 10000 );
    my $nelem = nelem($pdl);

    for ( my $i = 0; $i < $nelem; ++$i ) {
        my $val = $pdl->index($i);

        #Do something
    }

    return;
}

sub perl_scalar_value {
    my $pdl           = ones( float, 10000 );
    my $nelem         = nelem($pdl);

    for ( my $i = 0; $i < $nelem; ++$i ) {
        my $val = $pdl->at($i);

        #Do something
    }

    return;
}

##</code><code>##

              Rate  pdl_values perl_values
pdl_values  16.8/s          --        -74%
perl_values 64.1/s        282%          --

##</code><code>##

#!/usr/bin/env perl

use strict;
use warnings;

use PDL;
use Benchmark qw(:all);

cmpthese(
    100,
    {   'pdl_values'  => sub {&pdl_value},
        'perl_values' => sub {&perl_scalar_value},
    }
);


exit;

sub pdl_value {
    my $pdl = ones( float, 10000 );
    $pdl->index(0) .= 999;
    my $nelem         = nelem($pdl);
    my $special_value = 999;

    my @values;
    for ( my $i = 0; $i < $nelem; ++$i ) {
        my $val = $pdl->index($i);
        if ( $val == $special_value ) {
            $val = undef;
        }
        push @values, $val;
    }

    #Do something with @values
    return;
}

sub perl_scalar_value {
    my $pdl = ones( float, 10000 );
    $pdl->index(0) .= 999;
    my $nelem         = nelem($pdl);
    my $special_value = 999;

    my @values;
    for ( my $i = 0; $i < $nelem; ++$i ) {
        my $val = $pdl->at($i);
        if ( $val == $special_value ) {
            $val = undef;
        }
        push @values, $val;
    }

    #Do something with @values
    return;
}


##</code><code>##

              Rate  pdl_values perl_values
pdl_values  1.51/s          --        -97%
perl_values 52.1/s       3347%          --

##</code><code>##

pdl> $a = xvals(5)*2; # $a is a PDL
pdl> $a4 = $a->at(4); # $a4 is a perl scalar

##</code><code>##

pdl> @a = $a->list; pdl> for($a->list) { print $_, - ; }
0-2-4-6-8-