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dpssclear

Remove discrete prolate spheroidal sequences from database

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Syntax

dpssclear(seqLength,timeHalfBW)

Description

dpssclear(seqLength,timeHalfBW) removes sequences with length seqLength and time-half-bandwidth product timeHalfBW from the DPSS MAT-file database dpss.mat. Create the dpss.mat file using dpsssave.

example

Examples

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Open Live Script

Generate four Slepian sequences. Each sequence has 128 sequences and time-half-bandwidth product of 3, 6, 9, and 12. 

sL = [128 128 128 128]; % Segment length
tHBW = [3 6 9 12]; % Time-half-bandwidth product
for k=1:length(sL)
    [dpsSeq,lambda] = dpss(sL(k),tHBW(k));
    dpsssave(tHBW(k),dpsSeq,lambda);
end

Clear the sequence with a time-half-bandwidth product of 6.

seqLength = 128;
timeHalfBW = 6;

dpssclear(seqLength,timeHalfBW);

List the variable information of the modified Slepian sequence database file. The second sequence is empty.

whos -file dpss.mat
  Name            Size            Bytes  Class     Attributes

  E1            128x6              6144  double              
  E2              0x0                 0  double              
  E3            128x18            18432  double              
  E4            128x24            24576  double              
  V1              6x1                48  double              
  V2              0x0                 0  double              
  V3             18x1               144  double              
  V4             24x1               192  double              
  index           1x1              1091  struct              
  next_key        1x1                 8  double

Input Arguments

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Sequence length, specified as a positive integer.

Data Types: single | double

Time-half-bandwidth product, specified as a positive scalar. This argument must be less than seqLength/2.

Data Types: single | double

More About

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Structure of DPSS MAT- file Database

The dpsssave function creates and stores a file named dpss.mat with the DPSS (Slepian sequences) that you generate with the dpss function.

The dpsssave function assigns a location key (1, 2, …, n) and a name (E1, V1, E2, V2, ..., En, Vn) for each Slepian sequence that it generates and stores it in the dpss.mat file, from the first to the nth sequence.

A dpss.mat file with n sequences presents the following structure:

  • E1, E2, …, En — Slepian sequences.

  • V1, V2, …, Vn — Frequency-domain energy concentration ratios.

  • index — Database index, a struct array with information of the list of sequence lengths, time-half bandwidth products and locations of the Slepian sequences stored in the DPSS MAT-file database. This structure array comprises of the following fields:

    • N — Vector of sequence lengths. The dpsssave function assigns a single entry in N for each different value of sequence length.

    • Wlist — Structure array of time-half bandwidth products NW and sequence location numbers key. The dpsssave function assigns a sequence location key to each Slepian sequence each time you call it.

  • next_key — Next-sequence identification key, defined as next_key=n+1 where n is the number of Slepian sequences stored in the DPSS MAT-file database.

Version History

Introduced before R2006a

See Also

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