Calculating cost of debt (redeemable debt) vs. Yield to maturity

Dear John, Is the calculation of the two mentioned above the same by using the IRR? I am just a little confused, why in the calculation in the ACCA article "Bond valuation and bond yields" the current bond price is being deducted from the PV of the low interest rate in the IRR calculation whereas in the calculation of the cost of debt (redeemable debt) it is not deducted? Thank you so much!