This FAQ addresses some important questions with respect to the NaN and BIOSIG-toolbox.
Q1: WHAT IS THE NAN-TOOLBOX?A1: The NaN-toolbox contains foundamental statistical functions, which resemble the standard statistical functions of Octave and Matlab but with one difference. The NaN-toolbox ignores (and skips) all NaN's in the data. More information on the BIOSIG toolbox can be obtained from here:
http://bci.tugraz.at/~schloegl/matlab/NaN/ biosig/../NaN/README.TXT http://biosig.sourceforge.net/help/NaN/index.html Q2: HOW DOES THE NAN-TOOLBOX AFFECT OTHER APPLICATIONS?A2: As long as there are no NaN's in the data, the results are exactly the same. If your data contains NaN, the functions in the NaN-toolbox ignores them. Standard matlab will propagate NaN's, consequently, the output gives NaN.
Q3: WHY IS THE NAN-TOOLBOX BUNDLED WITH BIOSIG ?A3: Several important features of the BIOSIG toolbox are based on the features of the NaN-toolbox: - NaN provides an efficient encoding of missing data (no need of extra memory)
- Artifacts and breaks kann be encoded with NaN's.- Several signal processing methods rely on the NaN-toolbox for correct handling of missing data.
- TRIGG uses NaN to provide a decorrelation between trials. - SLOAD uses NaN to indicate breaks between concatanated recordings. - The NAN-TOOLBOX supports BIOSIG in handling of data with missing values. Q4: WHAT'S THE EXPERIENCE WITH THE NaN-TOOLBOX?A4: I'm using this toolbox since about 1998; without any severe problem. Many users worldwide are using it also since several years, too. The NaN-toolbox has been bundled with the BIOSIG-toolbox because of its usefulness. Without the NaN-toolbox, You abandon many useful features of BIOSIG. I clearly recommend to use it.
Q5: DOES THE NAN-TOOLBOX SLOW DOWN MATLAB APPLICATIONS?A5: Many functions in the NaN-toolbox are based on SUMSKIPNAN. There is an M-file and a MEX-file implementation of SUMSKIPNAN. By default, the slower M-file implementation is used. However, you can compile
the MEX-FILE for your platform with the command MEX SUMSKIPNAN.CPP. Best, Alois Schloegl