Just a note. I believe the Erf function is 1 for numbers just short of 6 at
full machine precision.
You may want to consider:
If (Abs(x) =6 Then my_erf = 1

If (Abs(x) 27) Then
my_erf = 1

--
Dana DeLouis
Using Windows XP & Office XP
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"Dana DeLouis" wrote in message
...
Not sure, but if 'x' were -2, is this what you are trying to do?

Sub Demo()
Dim v
v = Sgn(-2) * [Erf(Abs(-2))]
End Sub

Note that in VBA, the "Sign" function is called "Sgn" (Worksheet, it is
'Sign')

HTH
--
Dana DeLouis
Using Windows XP & Office XP
= = = = = = = = = = = = = = = = =