tests/testthat/examples/lorenz_deSolve.R

In richfitz/odin: ODE Generation and Integration

sir <- function() {
  sigma <- 10.0
  R     <- 28.0
  b     <-  8.0 / 3.0

  initial <- function(t = 0, pars = NULL) {
    c(10, 1, 1)
  }

  derivs <- function(t, y, .) {
    y1 <- y[[1L]]
    y2 <- y[[2L]]
    y3 <- y[[3L]]
    list(c(sigma * (y2 - y1),
           R * y1 - y2 - y1 * y3,
           -b * y3 + y1 * y2))
  }

  list(derivs = derivs, initial = initial, t = c(0, 15))
}