June 8th, 2010, 2:02 am
I have two separate implementations of Hull-White ? one of them is based on a paper titled ?Using Hull-White Interest-Rate Trees? and the second based on a paper they wrote some time later, called ?The General Hull-White Model and Super Calibration?. I am certain the implementations are correct, given that the trees they generate are the same as the examples in the papers, but when I use the same example in both models, I end up with different trees. Both trees seem to be calibrated correctly, but the shape of the trees, the values at the nodes, and the probabilities are different. I?m not sure I understand how this would be possible, given that the underlying process should be the same. Has anyone seen this? Is there a possible explanation beyond errors in the code? I?ve run several examples based on examples in books (most of them based on the first paper), and I seem to be getting the expected results. Still both implementations yields different results when the same example is run on each.