Computes the short- and long-axis standard deviations of the
Poincare plot: SD1 (short-term variability) and SD2 (long-term).
Arguments
- rr
Numeric vector of RR intervals in milliseconds.
Value
List with value (SD1), name, and extra
(sd1, sd2, sd1_sd2_ratio, n_intervals).
Details
Reference: Brennan, M., Palaniswami, M. & Kamen, P. (2001) "Do existing
measures of Poincare plot geometry reflect nonlinear features of heart
rate variability?", IEEE Trans. Biomed. Eng. 48(11):1342–1347.
Examples
# \donttest{
set.seed(1)
rr <- 800 + cumsum(rnorm(200, sd = 20))
res <- hrvnl(rr)
res$extra$sd1
#> [1] 13.15566
# }