R: Internal deSolve Functions

deSolve-internal {deSolve} | R Documentation

## Internal deSolve Functions

### Description

Internal deSolve functions, these are not to be called by the user.

### Usage

    timestep(prev = TRUE)

### Arguments

`prev` | if `TRUE` will return the timestep previously used; when `FALSE` will return the time step to be currently tried by the integrator.

### Details

Function `timestep` is intended to return the current or next timestep of the integration. It works only under specific circumstances and should not be used by the end user.

Instead of this, please see the example below for a pure R solution.

### See Also

`diagnostics` for information about the time steps used,
`lagvalue` and `lagderiv` that can be used for DDEs.

### Examples

    ###################################################
    ### This example shows how to retrieve information
    ### about the used time steps.
    ###################################################

    ## a function closure  ('lexical scoping')
    modelClosure <- function(t0) {
      t.old <- t.act <- t0
      function(t, y, parms) {
        t.old  <<- t.act
        t.act  <<- t
        cat(t, "\t", t - t.old, "\n")
        with (as.list(c(y, parms)), {
          dP <- a * P      -  b * P * K
          dK <- b * P * K  -  c * K
          list(c(dP, dK))
        })
      }
    }

    model <- modelClosure(0) # initialization

    parms <- c(a = 0.1, b = 0.1, c = 0.1)

    y <- c(P = 1, K = 2)

    out <- ode(y = y, func = model, times = c(0, 2),
     parms = parms, method = "lsoda")

    ls() # prove that t.old and t.new are local within 'model'

[Package deSolve version 1.21 Index]