WaveThresh
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example.1
Compute and return piecewise polynomial coordinates.
DESCRIPTION
This function computes and returns the coordinates of the
piecewise polynomial described by
Nason and Silverman, 1994.
This function is a useful test function for evaluating wavelet shrinkage
methodology as it contains smooth parts, a discontinuity and it is
periodic.
USAGE
example.1()
REQUIRED ARGUMENTS
None.
OPTIONAL ARGUMENTS
None
VALUE
A list with two components:
-
x
- a vector of length 512 containing the ordered x ordinates of the
piecewise polynomial.
-
y
- a vector of length 512 containing the corresponding y ordinates of
the piecewise polynomial.
SIDE EFFECTS
None
DETAILS
This function computes and returns the x and y coordinates of
the piecewise polynomial function described in
Nason and Silverman, 1994.
The formula for the piecewise polynomial (which is piecewise
cubic) is given in
Nason and Silverman, 1994 and
is
The piecewise polynomial returned is a discrete sample on 512
equally spaced points between 0 and 1 (including 0 but excluding 1).
The classic Donoho and Johnstone test functions can be generated using
the DJ.EX function.
RELEASE
Version 3.5.3 Copyright Guy Nason 1994
EXAMPLES
#
# Generate the piecewise polynomial
#
> test.data <- example.1()$y
> tsplot(test.data)
