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);