SHAH Discrete Shah-distribution Usage: f=shah(L,a); SHAH(L,a) computes the discrete, normalized Shah-distribution of length L with a distance of a between the spikes. The Shah distribution is defined by f(n*a+1)=1/sqrt(L/a) for integer n, otherwise f is zero. This is also known as an impulse train or as the comb function, because the shape of the function resembles a comb. It is the sum of unit impulses ('diracs') with the distance a. If a divides L, then the DFT of SHAH(L,a) is SHAH(L,L/a). The Shah function has an extremely bad time-frequency localization. It does not generate a Gabor frame for any L and a. Examples: --------- A simple spectrogram of the Shah function (includes the negative frequencies to display the whole TF-plane): sgram(shah(256,16),'dynrange',80,'nf')
Package: ltfat