i found another way, a bit faster probably:

my $d1 = 0;
my @min;
my @max;
for(0 .. $#data-1)
{
        my $d = $data[$_+1]-$data[$_];

        push 
          @{ $d<0 ? \@max : \@min }, 
          [$_, $data[$_]] 
        if $d*$d1<=0 && $d!=0

        $d1 = $d;
}
if($d1>0) {push @max, [$#data, $data[-1]];}
if($d1<0) {push @min, [$#data, $data[-1]];}

print "max $$_[1] at $$_[0]\n" for(sort {$b[1] <=> $a[1]} @max);
print "min $$_[1] at $$_[0]\n" for(sort {$a[1] <=> $b[1]} @min);
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$d*$d1 will be negative when the sign of $d and $d1 does not match, meaning that the the values passed from increasing to decreasing or vice-versa

Oha