Function Ave, a1, a2, a3, a4, a5, a6, a7

; This procedure will average 2-7 arrays. All the arrays are assumed to have the 
; same dimensions and no error checking is done for this.

On_Error, 1 ; Return to main IDL level
n = N_Params()
If n LT 2 Then $ ; Less than 2
   Message, 'Minimum of 2 input arrays required'
If n GT 7 Then $ ; More than 7
   Message, 'Maximum of 7 input arrays allowed'

dims = Size(a1) ; Arrays assumed to be same size
col = dims(1) & row = dims(2)

; Build array ['1', '2', '3', '4', '5', '6', '7']

idx = StrTrim(IndGen(7) + 1, 2) 

sum = FltArr(col,row)
output = FltArr(col, row)
;
For j=0, n-1 Do Begin

   ; Add the arrays together

   str = 'output = output + a' + idx(j)
   check1 = Execute(str)

	  ; Add the total for the divisor

   div = 'sum = sum + (a' + idx(j) + ' GT 0)'
   check2 = Execute(div) 

   If check1 EQ 0 OR check2 EQ 0 Then $
      Message, 'Function failed to execute'

EndFor

If (Min(sum) EQ 0) Then $ ; Check divide by 0
   sum(Where(sum EQ 0)) = 1

Return, output/sum
END