plotpkt. Given that this function plots
a wavelet packet box at a given level, packet index and with
particular shading and color and optionally plotting a sequence of
coefficients at that location rather than a shaded box.addpkt(level, index, density, col, yvals)yvals is plotted where
the box would have been.basisplot,basisplot.BP,
basisplot.wp, plotpkt, plot.nvwp