problems with localVolImpl

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problems with localVolImpl

Paulius Jakubenas
Dear all,

When getting a local volatility from implied volatility via
localVolImpl() (for example using a Monte Carlo simulation),
from time to time one is given a negative local volatility (which generates an exception - as expected).
The problem often arises  from small numerical inaccuracies which get
augmented when numerically calculating the second derivative.

Has anyone  already encountered and resolved the problem?
If not, I'd like to contribute a fix to the library. This would mean changing the interface s.t. the
LocalVolTermStructure::localVolImpl method returns a discretized vol - not an instantaneous vol.
This would be consistent with the library structure - as it is the Euler discretization method which
calls the local vol method.

Does anyone have any other suggestions?

Sincerely,
Paulius
 



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Re: problems with localVolImpl

Luigi Ballabio
Hi Paulius,

On Mon, 2008-02-18 at 13:01 +0000, Paulius Jakubenas wrote:

> When getting a local volatility from implied volatility via
> localVolImpl() (for example using a Monte Carlo simulation),
> from time to time one is given a negative local volatility (which
> generates an exception - as expected).
> The problem often arises  from small numerical inaccuracies which get
> augmented when numerically calculating the second derivative.
>
> Has anyone  already encountered and resolved the problem?
> If not, I'd like to contribute a fix to the library. This would mean
> changing the interface s.t. the
> LocalVolTermStructure::localVolImpl method returns a discretized vol -
> not an instantaneous vol.

I'm not sure that I'm following. What would the discretized vol be?

Later,
        Luigi


--

Don't let school get in the way of your education.
-- Mark Twain



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