@small = @numbers [0 .. $#small];
[download]

a correct solution? If not, why not?

I suggest you specify better how @small should look like - chances are you find a solution before posting the specificiation. And if not, you don't risk that a dozen people suggest answers, all doing something else than what you really want.

Abigail

#! perl -slw
use strict;

my @numbers = qw[
    76.8 77.0 77.2 77.4 77.6 77.8  78.0  78.2 78.4 78.6 78.8
    79.0 79.2 79.4 79.6 79.8 80.0  80.2  80.5 80.7 80.9 81.1
];

my @small = qw[ 78.6  78.8 79.0 80.9 77.0 ];

my $i=0;

$i++ until $numbers[ $i ] == $small[ 0 ];

@small = @numbers[ $i .. ( $i + $#small ) ];

print "@small";
__END__

P:\test>test
78.6 78.8 79.0 79.2 79.4
[download]

That can't be right. It assumes that the first element of @small is correct, but it was explicitely mentioned that the first element could be wrong.

Abigail

Reading between the lines of the post and attemptng to interprete the intent from the example given, I took the "even if first and last are incorrect" to mean the lowest and highest values in the small array.

This was the only interpretation I could make fit the data supplied.

---

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
If I understand your problem, I can solve it! Of course, the same can be said for you.

The statement of the problem is flawed. Since @numbers is sorted numerically, @small = sort {$a <=> $b } @small should be sufficient.

Unfortunately, his statement of what @small should be doens't seem to match the problem statement, in that @small actually contains 80.9, but what he says @small should be does *not* contain 80.9 - what are we to make of that?

my @numbers = qw(76.8 77.0 77.2 77.4 77.6 77.8  78.0  
                78.2 78.4 78.6  78.8 79.0 79.2 79.4 
                79.6 79.8 80.0  80.2  80.5 80.7 80.9 81.1);
 
my @small = qw(78.6  78.8 79.0 80.9 77.0);


$s{$_}++ for @small;

@ordered_small = grep { exists $s{$_} } @numbers;

# demo code below:
print "@ordered_small\n";

@numbers = reverse @numbers; 

@ordered_small = grep { exists $s{$_} } @numbers;

print "@ordered_small\n";
[download]

Update: On closer reading, the problem statement is hopeless. How are the numbers in small "selected", and what makes the first or last (or any other) number in @small "wrong"?

Update: After re-reading the question and reading the responses of others it's unlear what the original poster is asking.

Uhm, no, I don't think so. First, the big array is already sorted, that's a given, and so is the array in the example. Second, if you sort the second array, how would you which numbers of the smaller array are correct, and which arent'?

Abigail