Arrays

["Chris Evans" <evanscje@xxxxxxxxxxxxx>]

OK so I want to add up the last 3 up close
Differences using an array:
  
Array:Diff[3],(0);

If close>close[1] then
Diff[1]=close-close[1];

Sum=Diff[1]+Diff[2]+Diff[3];

But I don't think this works.. I thought that 
an array value would slide over each time a new 
value was put in the first array location ..- 
obviously not
 
Help(?)...