my @ccond =
    sub {
        $rddt[$_[0]] - sum(@rrdt[$_[0]-12 .. $_[0]-1]) / 12;
    },
    sub {
        $rddt[$_[0]] - sum(@rrdt[$_[0]-50 .. $_[0]-1) / 50;
    },
    sub {
        $rddt[$_[0]] - min(@rddt[$_[0]-5 .. $_[0]-1]);
    },
    # ...
);

##</code><code>##

    $cv = sprintf "%0.2f", $ccond[$cond]->($i);