PHP: calculate distance between two points

Each point is an one-dimensional array, each value in the array is a coordinate, so dimension of coordinates in this function is arbitriary.

 /*
 * Calculates Euclidian distance between two points in p-norm
 * Points $p1 and $p2 are Nx1 matrices
 */
 function euclidian_distance($p1,$p2) {
  if(count($p1) != count($p2)) return false;
  $distances = 0;
  
  $p1 = array_values($p1);
  $p2 = array_values($p2);
  
  $norm = count($p2);
  
  for($i=0;$i<$norm;$i++) $distances += pow(abs($p1[$i]-$p2[$i]),2);
  
  return pow($distances,1/2);
 }

Windows 7/Vista & ArcGIS & ESRI License Manager

It seems that ESRI License Manager has difficulties running in Windows 7 or Vista – the License server fails to start at boot or on demand in License Manager Tools.
Consequently, ArcGIS didn’t start because there was no license server running. Obviously this problem doesn’t occur if the license server is running on another machine in the network.
At first I tried the quick and dirty solution – to manually start the server daemon and see where it fails.
I ran Command Prompt as an administrator:

Now, the server is called lmgrd.exe, so if you navigate to C:\Program Files\ESRI\License\arcgis9x and start lmgrd, it says that there is no license specified.
So I typed the location of the license (it was in the same folder), ran the program in the foreground:
lmgrd –c license.lic -z
I kept the command prompt open, and ArcGIS started succesfully.
But this isn’t really a long term solution, since this method would require manual server start in the command prompt everytime I would want to start ArcGIS.
So I thought, maybe the problem is that the server can’t find the license file. After some googling, I found out that the environment variable LM_LICENSE_FILE wasn’t set. It says on the support page that you’d need to enter port@machine-name for the variable value, but since we’re running the server on the local machine, you just need to enter your C:\Path\to\your\license.lic.

When all goes well with License Manager Tools, you might still need to enter "localhost" in the ArcGIS desktop manager in the license server.
If anyone has a better solution or information, please post in the comments.
UPDATE:
After further experimentation I found out that you also need the Sentinel driver to successfuly run License Manager on Windows 7. Don't know why, but it works. You should install Sentinel driver first, then the license manager, so that everything for the license works before you install ArcGIS. That way you won't have to manually configure ArcGIS for license after it has been installed. You have less work that way.