Hello;

The following simple custom function returns #Value!
The function does not appear to activate mySheet, nor assigns a value to
NumOfRows.

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Function GEL_Reg_1 (mySheetIndex, arg1, arg2, arg3, arg4, arg5, arg6)
' mySheetIndex : from 1 to 16, is the index of the applicable w/s in this w/b
' NumOfRows : value bet ~200 to 600, is stored in cell C14 in mySheet. It
is the
' number of rows of coefficients, starting row 21 of mySheet. Each row has 7
' values; col C to col I. Values in col C are multipliers, so apply them
after the
' inner loop is complete.
'
Dim NumOfRows As Integer, myI As Integer, myJ As Integer
Dim mySum, mySumR
Dim mySheet As Worksheet
'
' create an array for the input parameters
myParm = Array (arg1, arg2, arg3, arg4, arg5, arg6)
'
' activate the w/s that has the relevant coefficients
Set mySheet = Worksheet (mySheetIndex)
mySheet.Activate
NumOfRows = Range ("C14")

mySum = 0
For myI = 1 To NumOfRows
myReg = Array (Cells(21 + myI - 1,3), Cells(21 + myI - 1,4), ...,
Cells(21 + myI - 1,9) )
mySumR = 1
For myJ = 1 To 6
mySumR = mySumR * myParm (myJ) ^ myReg (myJ + 1)
Next myJ
mySum = mySum + myReg(1) * mySumR
Next myI
GEL_Reg_1 = mySum
End Functio
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Your suggestions would be greatly appreciated. Thank you.