dpss
Discrete prolate spheroidal (Slepian) sequences
Syntax
dps_seq = dpss(seq_length,time_halfbandwidth)
[dps_seq,lambda] = dpss(seq_length,time_halfbandwidth)
[...] = dpss(seq_length,time_halfbandwidth,num_seq)
[...] = dpss(seq_length,time_halfbandwidth,'interp_method')
[...] = dpss(...,Ni)
[...] = dpss(...,'trace')
Description
dps_seq = dpss(seq_length,time_halfbandwidth)
returns the firstround(2*time_halfbandwidth)
discrete prolate spheroidal (DPSS), or Slepian sequences of lengthseq_length
.dps_seq
is a matrix withseq_length
rows andround(2*time_halfbandwidth)
columns.time_halfbandwidth
must be strictly less thanseq_length/2
.
[dps_seq,lambda] = dpss(seq_length,time_halfbandwidth)
returns the frequency-domain energy concentration ratios of the column vectors indps_seq
. The ratios represent the amount of energy in the passband [–W,W] to the total energy from [–Fs/2,Fs/2], whereFsis the sample rate.lambda
is a column vector equal in length to the number of Slepian sequences.
[...] = dpss(seq_length,time_halfbandwidth,num_seq)
returns the firstnum_seq
Slepian sequences with time half bandwidth producttime_halfbandwidth
ordered by their energy concentration ratios. Ifnum_seq
is a two-element vector, the returned Slepian sequences range fromnum_seq(1)
tonum_seq(2)
.
[...] = dpss(seq_length,time_halfbandwidth,'interp_method')
用插值compute the DPSSs from a user-created database of DPSSs. Create the database of DPSSs withdpsssave
and ensure that the resulting file,dpss.mat
, is in the MATLAB®search path. Valid options for'interp_method'
are'spline'
and'linear'
. The interpolation method uses the Slepian sequences in the database with time half bandwidth producttime_halfbandwidth
and length closest toseq_length
.
[...] = dpss(...,Ni)
interpolates from DPSSs of lengthNi
in the database dpss.mat.
[...] = dpss(...,'trace')
prints the method used to compute the DPSSs in the command window. Possible methods include: direct, spline interpolation, and linear interpolation.
Examples
More About
References
Percival, D. B., and A. T. Walden.Spectral Analysis for Physical Applications.Cambridge, UK: Cambridge University Press, 1993.