Calculate and Set Distributed Cache Size

#calculation from: http://technet.microsoft.com/en-us/library/jj219613.aspx
$membanks =get-wmiobject Win32_PhysicalMemory
$sum = 0
$i=1
foreach ($membank in $membanks)
{
 write-host "Capacity Memory $i = " ($membank.capacity/1024/1024)
 $sum = ($membank.capacity/1024/1024) + $sum
 $i=$i+1
}

write-host "Sum of Memory = " $sum

$cachesize = ($sum - 2048)/2
if ($cachesize>16384)
 {
  $cachesize=16384 #not more than 16GB
 }

write-host "Distributed Cachesize will be updated to: " $cachesize
Update-SPDistributedCacheSize -CacheSizeInMB $cachesize