Function TST (type As String, d_excel As Double) As Double


    With Application
        .ScreenUpdating = False
        .EnableEvents = False
        .Calculation = xlCalculationManual
    End With
    

type_value =type
d_value = d_excel

last_row = Worksheets("source_sheet").UsedRange.Rows.Count

type_array = Worksheets("source_sheet").Range("A6:A" & CStr(last_row)).Value    '<----- записываю все в массив, чтобы было быстрее
coef_a_array = Worksheets("source_sheet").Range("E6:E" & CStr(last_row)).Value
coef_B_array = Worksheets("source_sheet").Range("F6:F" & CStr(last_row)).Value



For i = 1 To UBound(type_array)
    If array(i, 1) = type_value Then
        coef_a = coef_a_array(i, 1)   '<----- для каждого типа свои коэф-ты
        coef_b = coef_B_array(i, 1)
        Exit For
    End If
Next


TST = Application.WorksheetFunction.Ln(d_value) * coef_a + coef_b


    With Application
        .ScreenUpdating = True
        .EnableEvents = True
        .Calculation = xlCalculationAutomatic
    End With

End Function