Chris@38: 
Chris@93: module yetilab.transform.window;
Chris@38: 
Chris@93: b = load yetilab.block.block;
Chris@93: bf = load yetilab.block.blockfuncs;
Chris@38: 
Chris@38: cosinewin a0 a1 a2 a3 n =
Chris@38:     b.fromList
Chris@38:        (map do i:
Chris@38:             a0
Chris@38:             - a1 * cos(2 * pi * i / n)
Chris@38:             + a2 * cos(4 * pi * i / n)
Chris@38:             - a2 * cos(6 * pi * i / n)
Chris@38:             done [0..n-1]);
Chris@38:                   
Chris@38: hann = cosinewin 0.5 0.5 0.0 0.0;
Chris@38: hamming = cosinewin 0.54 0.46 0.0 0.0;
Chris@38: blackman = cosinewin 0.42 0.50 0.08 0.0;
Chris@38: nuttall = cosinewin 0.3635819 0.4891775 0.1365995 0.0106411;
Chris@38: blackmanHarris = cosinewin 0.35875 0.48829 0.14128 0.01168;
Chris@38: boxcar = b.consts 0.5;
Chris@38: 
Chris@38: bartlett n =
Chris@38:     b.fromList
Chris@38:        (m = n/2;
Chris@38:         concat [
Chris@38:             map do i:
Chris@38:                 i / m
Chris@38:                 done [0..m-1],
Chris@38:             map do i:
Chris@38:                 1.0 - (i / m)
Chris@38:                 done [0..m-1]
Chris@38:             ]);
Chris@38: 
Chris@49: windowed windowFunc frames =
Chris@43:     case frames of
Chris@43:         []: frames;
Chris@43:          _: (first = head frames;
Chris@43:              window = windowFunc (b.length first);
Chris@43:              map (bf.multiply window) frames);
Chris@43:     esac;
Chris@43: 
Chris@38: {
Chris@43: cosinewin, hann, hamming, blackman, nuttall, blackmanHarris, boxcar, bartlett,
Chris@49: windowed
Chris@38: };
Chris@38: