Function Coef(t$, ordre%)
Dim s1, i As Byte, s2, j%, x%, n%
Coef = ""
s1 = Split(t, " => ")
If UBound(s1) <> 1 Then Exit Function
For i = 0 To 1
s2 = Split(s1(i), " + ")
For j = 0 To UBound(s2)
x = Val(s2(j))
If x = 0 Then x = 1
n = n + 1
If n = ordre Then Coef = IIf(i, x, -x): Exit Function
Next j, i
End Function