Go trough the file and remember what is the smallest and largest number in each column. Something like this (untested):
my $min_col_2 = 1_000_000; # Something large enough
my $max_col_2 = 0; # Something small enough
my $min_col_3 = 1_000_000; # Something large enough
my $max_col_3 = 0; # Something small enough
while(<>){
if(/^ZZ/){
my @array = split;
if($min_col_2 > $array[1]){
$min_col_2 = $array[1];
}
if($max_col_2 < $array[1]){
$max_col_2 = $array[1];
}
# Snip
}
}
To get the step size you also have to remember the second smallest number, and look at the difference between that and the smallest when you are done.
