# bkvolspec

Specify Black-Karasinski interest-rate volatility process

## Syntax

```Volspec = bkvolspec(ValuationDate, VolDates, VolCurve,AlphaDates, AlphaCurve, InterpMethod)```

## Arguments

 `ValuationDate` Scalar value representing the observation date of the investment horizon. `VolDates` Number of points `(NPOINTS)`-by-`1` vector of yield volatility end dates. `VolCurve` `NPOINTS`-by-`1` vector of annualized yield volatility values in decimal form. The term structure of `VolCurve` is the yield volatility represented by the value of the volatility of the yield from time `t` = 0 to time `t` + i, where i is any point within the volatility curve. `AlphaDates` `NPOINTS`-by-`1` vector of mean reversion end dates. `AlphaCurve` `NPOINTS`-by-`1` vector of positive mean reversion values in decimal form. `InterpMethod` (Optional) Interpolation method. Default is `'linear'`. See `interp1` for more information.

## Description

```Volspec = bkvolspec(ValuationDate, VolDates, VolCurve,AlphaDates, AlphaCurve, InterpMethod)``` creates a structure specifying the volatility for `bktree`.

## Examples

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### Create a Black-Karasinski Volatility Specification

This example shows how to create a Black-Karasinski volatility specification (VolSpec) using the following data.

```ValuationDate = '01-01-2004'; StartDate = ValuationDate; VolDates = ['12-31-2004'; '12-31-2005'; '12-31-2006'; '12-31-2007']; VolCurve = 0.01; AlphaDates = '01-01-2008'; AlphaCurve = 0.1; BKVolSpec = bkvolspec(ValuationDate, VolDates, VolCurve,... AlphaDates, AlphaCurve) ```
```BKVolSpec = FinObj: 'BKVolSpec' ValuationDate: 731947 VolDates: [4x1 double] VolCurve: [4x1 double] AlphaCurve: 0.1000 AlphaDates: 733408 VolInterpMethod: 'linear' ```