my @data = (
           ["1.6","2.2","3.4","3.6","5.4","6.2","7.1", "8.1", "9.0"],
           [    1,    2,    5,    6,    3,  15,    4,     3,     4],
           [ sort { $a <=> $b } (1, 2, 5, 6, 3, 15, 4, 3, 4) ]
         );

# create a hash of refs to the things you want to updated.
# This is only needed for the example, so that we can
# use the ininialized array above. Normally, the hash is just updated 
# each time a new element is added to the arrays in IcrData().
for $idx (0..$#{$data[0]} ) {
   $data_refs_hash{$data[0][$idx]} = \$data[1][$idx];
}

print join(", ", @{$data[1]}), "\n";

IncrData("3.4");
IncrData("3.5");
IncrData("9.5");
IncrData("1.1");
IncrData("9.5");

print "\n";
print join(", ", @{$data[0]}), "\n";
print join(", ", @{$data[1]}), "\n";
print join(", ", @{$data[2]}), "\n";

#produces 
1.1, 1.6, 2.2, 3.4, 3.5, 3.6, 5.4, 6.2, 7.1, 8.1, 9.0, 9.5
1, 1, 2, 6, 1, 6, 3, 15, 4, 3, 4, 2
1, 1, 1, 2, 2, 3, 3, 4, 4, 6, 6, 15