In theory FX rates are expected to grow at rate equal to interest rate 
differential.
In practise it is never true. Though you have 2 ways to calc your expected 
growth:  
1. empirical
2. int rate differential

Code I included is simple daily simulation, adjust parameters as you wish. 
However, quantiles can be obtained empirically, so simulation is not really 
needed. Also, what I did is daily simulation, which is useful for path 
dependent applications, in your case distribution at final time T is enough and 
this would make code faster.

Calibrating:
1. Volatility
lnS = lng(S_t/S_t-1)
muS = mean(lnS)
volS = sqrt(sum(lnS - muS))

or simply sd(lnS)

2. expected rate of return
a) empirical would just be mean(lnS)
b) interest rate differential: careful with compounding. Online will be simple 
compounding, need to convert it to continuous.

If you need any other further help/advice let me know. I would gladly support 
you if I understood what you are trying to achieve. Provide me with some 
data/workings so I can help you more.

Kind regards,--  
Dominykas Grigonis


On Friday, 17 January 2014 at 06:39, Jaimie wrote:

> Hi dominykas
>  
> First of all, thanks for Your help.
>  
> I'm trying to model try/eur exchange rate.  
> I would like to find out whether spot rate as of december 31st 2013 is normal 
> (is as expected)  or is not due to some external factors like political 
> inestability that could have affected its expected evolution.
> Therefore, i would like to calibrate the model based on data up to december 
> 31st 2012 and make forecasts 1 yr ahead to get its expected evolution  and 
> also to simulate and get what the quantile of spot rate as of december 31st 
> 2013 is, based on simulated values. Is It in the tail of the distribution? , 
> is It nearest to the expected value....?
>  
> If You have some code that would help me to get these goals, i would be 
> strongly grateful if you could share It.
>  
> Bests
>  
> Jaimie
>  
> Pd: forgive any spelling mistakes.
> Enviado desde mi iPhone
>  
> El 16/01/2014, a las 10:36, Dominykas Grigonis <[email protected] 
> (mailto:[email protected])> escribió:
>  
> > BS means black scholes model. Simply: S_1 = S_0 exp((mu - vol^2/2)t + vol 
> > dW), where dW ~ N(0,t)
> >  
> > Do not know about packages, if you want I can provide you some code. It is 
> > pretty simple if you know what you are doing. What are you trying to 
> > achieve? Do you want to get a view for the future? Price options? Or 
> > building some kind of strategy testing?  
> >  
> >  
> > Kind regards,--  
> > Dominykas Grigonis
> >  
> >  
> > On Thursday, 16 January 2014 at 04:14, Jaimie Villanueva wrote:
> >  
> > > Hi,  
> > >  
> > > I'm not experienced on this so, Could you tell me a bit more on this?
> > >  
> > > What BS stands for and what are the package/s i should go to?
> > > I would need to calibrate the parameter of the model as well as simulate 
> > > values.
> > >  
> > > Bests
> > >  
> > > Jaimie
> > >  
> > >  
> > > On Wed, Jan 15, 2014 at 8:34 PM, Dominykas Grigonis 
> > > <[email protected] (mailto:[email protected])> wrote:
> > > > Exchange rates are not mean reverting. Simple BS with interest rate 
> > > > differential is usually applied.  
> > > >  
> > > >  
> > > > Kind regards,--  
> > > > Dominykas Grigonis
> > > >  
> > > >  
> > > > On Wednesday, 15 January 2014 at 19:30, Jaimie wrote:
> > > >  
> > > >  
> > > >  
> > > > > Hi R users
> > > > >  
> > > > > I'm trying to model fx rates with one-factor models like CIR, 
> > > > > Vasicek, hull-white etc. Those usually used in the context of 
> > > > > interest rate modeling.  
> > > > > I was wondering:
> > > > >  
> > > > > 1- Would It make sense? I mean, applying short rate models to 
> > > > > exchange rates.  
> > > > >  
> > > > > 2- What would be the best r package i should go to? Is there one 
> > > > > specially recomended?  
> > > > >  
> > > > > Thanks a lot in advanced.
> > > > >  
> > > > > Jaimie
> > > > >  
> > > > > Enviado desde mi iPhone
> > > > > _______________________________________________
> > > > > [email protected] (mailto:[email protected]) 
> > > > > mailing list
> > > > > https://stat.ethz.ch/mailman/listinfo/r-sig-finance
> > > > > -- Subscriber-posting only. If you want to post, subscribe first.
> > > > > -- Also note that this is not the r-help list where general R 
> > > > > questions should go.
> > > > >  
> > > > >  
> > > > >  
> > > >  
> > > >  
> > >  
> > >  
> > >  
> > > --  
> > > Jaimie.  
> >  

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