Piecewise polynomial function

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Description

This function generates Piecewise polynomial function values for n equally spaced points in [0,1].

Usage

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ppoly(norx=1024)

Arguments

norx

the number of data or x values in [0, 1]

Details

Piecewise polynomial function with the discontinuity is introduced by Nason and Silverman (1994) and is useful test function evaluating a wavelet shrinkage method.

Value

Piecewise polynomial function values f(i/n), i=1,…,n and its variability ||f|| = ∑_{i=1}^n (f_i - mena(f))^2 / (n-1) where mena(f) = ∑_{i=1}^n f_i / n.

References

Nason, G.P. and Silverman, B.W. (1994) The discrete wavelet transform in S. Journal of Computational and Graphical Statistics, 3, 163–191.

See Also

dopp, heav, fg1.

Examples

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testpoly <- ppoly(1024)
plot(testpoly$x, testpoly$meanf, xlab="", ylab="", 
     main="Plot of Piecewise polynomial function", type="l")