Local Cosine Transform
DESCRIPTION:
Computes local cosine transform.
USAGE: 
block.dct(x, n.levels=6, dct.type=2)
block.cpt(x, n.levels=6, taper="poly2", dct.type=2,
          boundary="periodic", n.taper=NULL)
as.block.cpt(x)
REQUIRED ARGUMENTS:
x:
a vector or univariate time series. Should demean first. The length of x should be divisible by 2^n.levels. For as.block.cpt only, x should be of class ptable (cosine packet table).
OPTIONAL ARGUMENTS:
n.levels:
a non-negative integer specifying the blocking factor: x is divided into 2^n.levels blocks each of length n/2^n.levels where n=length(x). If n.levels is bigger than ml, where ml is the maximum possible level, computed from the max.level function, then n.levels is set to ml and a warning message is given.
dct.type:
one of 2 or 4 indicating which of DCT-II or DCT-IV should be used. See the function dct for details.
taper:
a character string, indicating the taper function: "boxcar", "poly1", "poly2", "poly3", "poly4", "poly5", or "trig". See the function cp.table for details.
boundary:
for block.cpt only, one of the character strings: "cp.reflect", "periodic", or "zero", indicating the boundary extension rule. See the function cp.table for details.
n.taper:
a non-negative integer. The length of the taper will be 2*n.taper. By default, n.taper is set to length(x)/2^(n.level+1), which is the maximum possible length at the finest blocking level.
VALUE:
block.dct returns a block DCT transform object which has class block.dct, inheriting from the classes block.cpt, cpt, cp, and crystal.vector.

block.cpt returns a block cosine packet transform object which has class block.cpt, inheriting from the classes cpt, cp, and crystal.vector.

as.block.cpt returns an object of block.cpt (if x is an object of class ptable).

See crystal.vector.object for details about the data structure.

DETAILS:
x is divided into 2^n.level blocks, the blocks are tapered according to taper, and the DCT is applied to the tapered block.

All the default optional arguments can be reset using function wavelet.options, see wavelet.options for details.

REFERENCES:
Wickerhauser, M. V. (1994). Adapted Wavelet Analysis -- from theory to software.
SEE ALSO:
cpt , cp.table , dct , max.level , wavelet.options .
EXAMPLES: 
x <- make.signal("linchirp")
blx <- block.dct(x, n.levels=3)
eda.plot(blx)