lpfilt: Low pass filter.
In tunelipt/wutils: Useful functions for data processing in a wind tunnel

Description Usage Arguments Value Examples

Uses link{mvfft} to compute a low pass filter to the data.

1	lpfilt(x, freq, dt = NULL)

`x`	Vector or matrix containing data to be filtered. If matrix, each column corresponds to a time series.
`freq`	Frequency below which data will be filtered.
`dt`	Time steps betweend samples. If not specified, `x` is assumed to be a time series `ts` object.

The filtered signal

 tt <- seq(0, 4, len=513)[1:512]
 dt <- tt[2]
 x = ts(cos(4*pi*tt) + 1.5*sin(2*pi*tt) + 3 + cos(6*2*pi*tt),start=0,
 deltat=dt)
 xlp <- lpfilt(x, 1.5)
 plot(x, ylim=range(x, xlp))
 lines(xlp, lty=2)
legend(0, max(x, xlp), c("Signal", "Filtered Signal"), lty=c(1,2))