Sub Tab1toTab2()
Dim tabInit() As Variant
Dim tabFinal() As Variant
With Sheets("Data")
fin = .Range("A" & .Rows.Count).End(xlUp).Row
tabInit = .Range("A1:F" & fin).Value
taille = (UBound(tabInit, 1) - 2) * UBound(tabInit, 2)
ReDim tabFinal(1 To taille, 1 To 3)
j = 1
For i = 2 To UBound(tabInit, 1)
For k = LBound(tabInit, 2) + 1 To UBound(tabInit, 2)
tabFinal(j, 1) = tabInit(i, 1)
tabFinal(j, 2) = tabInit(1, k)
tabFinal(j, 3) = tabInit(i, k)
j = j + 1
Next k
Next i
End With
With Sheets("RES")
.UsedRange.Offset(1, 0).Clear
.Range("A2").Resize(UBound(tabFinal, 1), UBound(tabFinal, 2)) = tabFinal
End With
End Sub