Option Explicit
Public Sub Yulya()

Dim x(10), z(10, 10) As Single
Dim i, j As Byte

For i = 1 To 10
    x(i) = Cells(i + 1, 1).Value
    Next i

For i = 1 To 10
    For j = 1 To 10
        If ((x(i) <= 3.8) And (j = 1)) Then z(i, j) = x(i) Else: z(i, j) = 0
        Next j
    Next i

Cells(1, 6).Value = "Матрица z"
For i = 1 To 10
    For j = 1 To 10
        Cells(i + 1, j + 1).Value = z(i, j)
        Next j
    Next i
End Sub