#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my $min_elements = 11;
my $rLoLoL =[ [ [78,43,87], [64,73,72], [99], [65,67,71]      ],
              [ [1,2,3],    [4,5],      [6,7],[8, 9, 10, 11]  ],
            ];

@$rLoLoL = grep {
                  (my @elements = map{@$_}@$_)>= $min_elements
                }@$rLoLoL;
                
#some explanation ...most folks posting in this thread have
#thousands of posts and are experienced..but perhaps this will
#help others...although most folks don't go down this deep
#into the thread...

#the @$rLoLoL gets the list of references to matrices, the
#list of lists of lists (LoLoL).
# in: ...map{@$_}@$_), this last @$_ gets List of List's
# the map{} takes each one of these and "flattens the matrix
# out", what goes into @elements is like (78,43,87,64,73,72,99,65,67,71).
# 

print Dumper ($rLoLoL);
#the first "matrix" with 10 total elements has been removed...
__END__
Prints:
$VAR1 = [
          [
            [
              1,
              2,
              3
            ],
            [
              4,
              5
            ],
            [
              6,
              7
            ],
            [
              8,
              9,
              10,
              11
            ]
          ]
        ];