信用リスクによる利益訂正

最近pricederivatives.comの方程式を見ながらススワップの値段を計算しようとしています。The initial computation for CVA is present value of notional (positive)*recovery rate*Counterparty CDS spread*number of years. Strangely, though, the cited spreadsheet, using the "quantlib" library, obtains a result different from mine. The exposure is hedged via CDS, and the CDS cash premiums are considered to be the CDS spread times the exposure. Strangely, the "tenor" parameter is set to three months, meaning that the payments are made every three months. For an exposure of 79200, this would mean a payment of 396 every three months. However, 20 payments of 396 beginning today has a present value of 7556, as opposed to 7630 suggested by the spreadsheet. It is unclear whether misunderstandings about the day count convention are the cause of the discrepancy.