Ok, they say "never assume", but I'm gonna suggest a different answer than the others given so far, based on the following assumption: Aren't your arrays actually triplets of coordinates, each triplet ($x[$i], $y[$i], $z[$i]) representing a point in 3D?

If that is the case, might I suggest a change in data structures?
my @points;

# This will add one point (the first one in your arrays 
# above) to another type of data structure.
my %this_point = {x => 0, y => 0, z => 25};
push @points, \%this_point;

# Do this for as many points as you have. You can
# adapt the method you use to fill your three arrays
# to create this kind of data structure using the 
# example above.

[download]
That would allow you to refer to the X component of a point $i as:
$points[$i]->{x}

Then, the sorting becomes a bit easier:
# Sort by z first, then sort by x for each point
@points = sort { $a->{x} <=> $b->{x} } 
               sort { $a->{z} <=> $b->{z} }
                    @points;

[download]
(note: untested, but should give you the idea)

I find this data structure more intuitive, since the triplets of coordinates, which are related (they form a point in 3D), are actually together in the data structure, whereas in the arrays in your original post they are separated.

In reply to Re: Sorting issues by Skylark
in thread Sorting issues by hokie

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