Add the following macro to a button:

Sub MatrixFill()

With ActiveSheet
ActiveWorkbook.Sheets("table2").Range("A1:AV48").C ells(.Range("A1"), .Range("A2"))
= .Range("A3")
End With

End Sub

' table2 stands for the name of the sheet with the matrix
' A1:AV48 is the range on that sheet
' A1 is the Y location
' A2 is the X location
' A3 is the value

adapt the ranges and name of the sheet.

Hubisan