SimTrend: Simulate trend and breakpoints of a surrogate time series
In greenbrown: Land Surface Phenology and Trend Analysis

The function simulates the trend component with breakpoints of a time series.

SimTrend(slope = c(0.002, 
    -0.004), breaks = 165, 
    abrupt = TRUE, n = 360, 
    start = c(1982, 1), 
    freq = 12)

`slope`	`slope` of the trend in each time series segment. `slope` should be a numeric vector. The length of this vector determines the number of segments.
`breaks`	position of the breakpoints in the time series. You should specify one more `slope` than breakpoint.
`abrupt`	Should the trend at the breakpoints change `abrupt` (`TRUE`) or gradual (`FALSE`)?
`n`	length of the time series
`start`	beginning of the time series (i.e. the time of the first observation). The default is c(1982, 1), i.e. January 1982 which is the usual `start` date to compute trends on long-term series of satellite observations of NDVI. See `ts` for further examples.
`freq`	The frequency of observations. The default is 12 for monthly observations. Use 24 for bi-monthly observations, 365 for daily observations or 1 for annual observations. See `ts` for further examples.