[Quantlib-users] What's Bond Engine is for ql.CallableZeroCouponBond

[Josh C. <jc...@fa...>]

Dear QL community,
Need to price callable zero coupon bond (ZCB) by QuantLib-Python.
>From tech document on-line as below. I use  ql.CallableZeroCouponBond
https://rkapl123.github.io/QLAnnotatedSource/d4/ddb/class_quant_lib_1_1_callable_zero_coupon_bond.html

I know the basic application and example about pricing bond object by QL. 
Below code I'm doing this ZCB testing example. 
The find out from result is that  ql.CallableZeroCouponBond + ql.TreeCallableFixedRateBondEngine
This pricing module seems get wrong price. 
Anyone know how to pricing ZCB by correct BondEngine ? 
thanks. 

#*************************************************************************************************************************************
*import QuantLib as ql***
**
*calc_date = ql.Date(31,12,2023)***
*ql.Settings.instance().evaluationDate = calc_date***
*day_count = ql.ActualActual(ql.ActualActual.Bond)***
*rate = 0.035***
*ts = ql.FlatForward(calc_date,***
*                    rate,***
*                    day_count,***
*                    ql.Compounded,***
*                    ql.Semiannual)***
*ts_handle = ql.YieldTermStructureHandle(ts)***
**
*CallSch = ql.CallabilitySchedule()***
*CallSch.append(ql.Callability(ql.BondPrice(104,ql.BondPrice.Clean), ql.Callability.Call, ql.Date(15,1,2016)))***
*CallSch.append(ql.Callability(ql.BondPrice(136.8569,ql.BondPrice.Clean), ql.Callability.Call, ql.Date(15,1,2023)))***
*CallSch.append(ql.Callability(ql.BondPrice(180.0943,ql.BondPrice.Clean), ql.Callability.Call, ql.Date(15,1,2030)))***
*CallSch.append(ql.Callability(ql.BondPrice(236.9919,ql.BondPrice.Clean), ql.Callability.Call, ql.Date(15,1,2037)))***
*CallSch.append(ql.Callability(ql.BondPrice(311.8651,ql.BondPrice.Clean), ql.Callability.Call, ql.Date(15,1,2044)))***
*CallSch.append(ql.Callability(ql.BondPrice(324.3398,ql.BondPrice.Clean), ql.Callability.Call, ql.Date(15,1,2045)))***
**
*ZCBobj= ql.CallableZeroCouponBond(2,3000000,ql.TARGET(),ql.Date(15,1,2045),*
*            ql.Thirty360(ql.Thirty360.ISDA),ql.Following,324.3398,ql.Date(15,1,2015),CallSch)***
**
*a = 0.03***
*s = 0.12***
*grid_points = 40***
*model = ql.HullWhite(ts_handle, a, s)***
*engine = ql.TreeCallableFixedRateBondEngine(model, grid_points)***
*ZCBobj.setPricingEngine(engine)***
*ZCBobj.cleanPrice()***
*Out[25]: 11.938197755007225***
*ZCBobj.NPV()***
*Out[26]: 358044.0890306983*


Best, Josh
-----------------
"Talk is cheap. Show me the code." By Linus Torvalds.