Fixed-step 4th-order Runge-Kutta ODE integrator (base R, no dependencies)

A small, dependency-free ODE solver intended for building the simulate_fn ingredient MBMM needs (see mbmm_abc_fit). For stiff systems or very fine control, use deSolve instead – this function exists so the package (and its examples) do not require any package beyond base R.

Usage

mbmm_rk4_solve(f, y0, times, parms, n_substeps = 10)

Arguments

f

function(t, y, parms) returning the derivative dy/dt as a numeric vector the same length as y

y0

numeric vector of initial states

times

numeric vector of output times (need not be evenly spaced); the first element is treated as t0 with state y0

parms

a list or named vector passed through to f

n_substeps

number of RK4 substeps to take between each pair of consecutive times (higher = more accurate, slower)

Value

a matrix with one row per element of times and one column per state variable (plus a leading time column)