WaveletComp (version 1.0)

periodic.series: Computation of a (deterministic) periodic time series of linearly changing period.

Description

It computes and returns a sinusoid of a specified length, which has the given initial phase, and linearly changing periods (if requested) starting from a given period length through the given length at the end. There is an option to plot the time series.

Usage

periodic.series(start.period = 100, end.period = start.period,  phase = 0,  length = 600,  make.plot = F)

Arguments

start.period

period length at start (in steps of time). Default: 100

end.period

period length at end (in steps of time). Default: 50

phase

phase difference (in steps of time), i.e. part of period length which has elapsed relative to the origin. Default: 0

length

number of time steps. Default: 600

make.plot

Plot time series? Logical. Default: FALSE

Value

the series as vector

Details

This function can be used for illustrating methods and functions. Producing a sinusoid, periodic.series will work best if start.period (and end.period, if different from start.period) are not too small.

See Also

analyze.wavelet, wt.image, reconstruct

Examples

# The following time series involves periods from 100 through 50:
x = periodic.series(start.period = 100, end.period = 50, make.plot = TRUE)
title("time series with linearly changing period from 100 through 50")

# The following three time series involve three different types of period evolution 
# starting from period 100:
x1 = 0.8*periodic.series(start.period = 100, end.period = 95, phase = 0, length = 1000)
x2 =     periodic.series(start.period = 100, end.period = 100, phase = 0, length = 1000)
x3 = 1.2*periodic.series(start.period = 100, end.period = 105, phase = 0, length = 1000)

ts.plot(x2, ylim = c(-2, +2), xlab = "time", ylab = "series with variable period")
lines(x1, col = "blue")
lines(x3, col = "red")
legend("topleft", legend = c("speeding up (end period = 95)", "period = 100", 
   "slowing down (end period = 105)"), 
   lty = 1, col = c("blue", "black", "red"))