# Functions

- ★ How do I interpret the calculated EWMA values?
- How to identify the Nyquist frequency with DFT
- How do I know when cointegration exists in my results?
- EWMA (Exponential Weighted Volatility) FAQ
- Q: GARCH_CHECK returns true even when the sum of alpha and beta equals to one?
- Where is X-12-ARIMA?
- Can I compute the logarithmic return from a time series without any intermediate calculations?
- How can I compute the expiry date of an equity option?
- How can I use NumXL to compute the correlation matrix for 2 time series?
- How do I test whether a given time series is just noise?
- How do I use differencing to obtain a stationary time series?
- How do I use NumXL functions in my Excel sheet?
- When I run the ARMA model for my time series, the generated values for Phi and Theta are all zeros!
- When I try to use the calibration icon, an error message pops stating that solver is not found.
- Why does the calibration function in NumXL shows the constraint's rhs of 0.9999?
- Can I use NumXL function with VBA or in an Excel macro?
- How do I compute the current volatility?
- NumXL is not loading in Excel 2001-2003.
- Run-time error 5, invalid procedure call or argument?