odeToLin: Convert ODE-based linear compartment models to analytical...

In rxode2: Facilities for Simulating from ODE-Based Models

Convert ODE-based linear compartment models to analytical linCmt() form

Description

Detects whether a model's ODE equations form a standard 1-3 compartment PK system and, if so, replaces the d/dt() equations and the central output assignment (e.g. cp <- central/v) with cp <- linCmt(), preserving all other model lines. Detection requires linear ODE right-hand sides, 1-4 compartments in a standard depot/central/peripheral topology, and one output line of the form var <- central_cmt / v_expr. Named parameter assignments are retained so linCmt() can infer the parameterization.

Usage

odeToLin(ui)

Arguments

ui	rxUi-like model object (function, rxUi, or anything accepted by as.rxUi).

Value

An rxUi model with ODE equations replaced by linCmt(), or (with a message) the original model unchanged if conversion is not possible.

Author(s)

Matthew Fidler

See Also

linToOde for the inverse transformation.

Examples

oneCmtOde <- function() {
  ini({
    tka <- 0.45
    tcl <- log(2.7)
    tv <- 3.45
    add.sd <- 0.7
  })
  model({
    ka  <- exp(tka)
    cl  <- exp(tcl)
    v   <- exp(tv)
    d/dt(depot)   <- -ka * depot
    d/dt(central) <- ka * depot - cl/v * central
    cp <- central / v
    cp ~ add(add.sd)
  })
}
linCmtModel <- odeToLin(oneCmtOde)

rxode2 documentation built on July 28, 2026, 5:08 p.m.