[g,info] = wilwin(g,M,L);
[g,info]=wilwin(g,M,L) computes a window that fits well with the specified number of channels M and transform length L. The window itself is specified by a text description or a cell array containing additional parameters.
The window can be specified directly as a vector of numerical values. In this case, wilwin only checks assumptions about transform sizes etc.
[g,info]=wilwin(g,M) does the same, but the window must be a FIR window, as the transform length is unspecified.
The window can be specified as one of the following text strings:
| 'gauss' | Gaussian window with optimal concentration |
| 'dualgauss' | Riesz dual of Gaussian window with optimal concentration. |
| 'tight' | Window generating an orthonormal basis |
In these cases, a long window is generated with a length of L.
It is also possible to specify one of the window names from firwin. In such a case, wilwin generates the specified FIR window with a length of M.
The window can also be specified as cell array. The possibilities are:
- {'gauss',...}
- Additional parameters are passed to PGAUSS
- {'dual',...}
- Dual window of whatever follows. See the examples below.
- {'tight',...}
- Orthonormal window of whatever follows.
It is also possible to specify one of the window names from firwin as the first field in the cell array. In this case, the remaining entries of the cell array are passed directly to firwin.
Some examples:
g=wilwin('gauss',M,L);
This computes a Gaussian window of length L fitted for a system with M channels.
g=wilwin({'gauss',1},M,L);
This computes a Gaussian window with equal time and frequency support irrespective of M.
gd=wilwin('gaussdual',M,L);
This computes the dual of a Gaussian window fitted for a system with M channels.
gd=wilwin({'tight','gauss'},M,L);
This computes the orthonormal window of the Gaussian window fitted for the system.
g=wilwin({'dual',{'hann',20}},M,L);
This computes the dual of a Hann window of length 20.
The structure info provides some information about the computed window:
- info.gauss
- True if the window is a Gaussian.
- info.tfr
- Time/frequency support ratio of the window. Set whenever it makes sense.
- info.wasrow
- Input was a row window
- info.isfir
- Input is an FIR window
- info.isdual
- Output is the dual window of the auxiliary window.
- info.istight
- Output is known to be a tight window.
- info.auxinfo
- Info about auxiliary window.
- info.gl
- Length of window.