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Project values with a predictor-corrector method

Source: R/project_n.R
project_n_2.Rd

This is an experimental second-order time stepping variant of project_n(). It first predicts the new consumer densities with project_n(), optionally recalculates rates from that prediction, and then applies a Crank-Nicolson corrector using midpoint rates.

Usage

project_n_2(
  params,
  r,
  n,
  dt,
  a,
  b,
  c,
  S,
  idx,
  w_min_idx_array_ref,
  no_sp,
  no_w,
  rates_fns = NULL,
  n_pp = NULL,
  n_other = NULL,
  t = 0,
  effort = NULL,
  r_hat = NULL,
  r_mid = NULL,
  ...
)

Arguments

params

A MizerParams object.

r

A list of rates as returned by mizerRates().

n

An array (species x size) with the number density at the current time step.

dt

Time step.

a

A matrix (species x size) used in the solver (transport term).

b

A matrix (species x size) used in the solver (diagonal term).

c

A matrix (species x size) used in the solver (transport term).

S

A matrix (species x size) used in the solver (source term).

idx

Index vector for size bins (excluding the first one).

w_min_idx_array_ref

Index vector for the start of the size spectrum for each species.

no_sp

Number of species.

no_w

Number of size bins.

rates_fns

Optional named list of rate functions, as used by mizerRates(). If supplied together with n_pp, n_other and effort, provisional end-of-step rates are calculated from the predicted densities.

n_pp

Resource abundance used when recalculating provisional rates.

n_other

Other ecosystem components used when recalculating provisional rates.

t

Current time.

effort

Fishing effort used when recalculating provisional rates.

r_hat

Optional provisional end-of-step rates. If supplied, these are used instead of recalculating them.

r_mid

Optional midpoint rates. If supplied, these are used directly in the Crank-Nicolson corrector.

...

Further arguments passed to the rate functions.

Value

The updated abundance density matrix n.

Details

If the rate recalculation arguments are not supplied, the corrector uses the supplied rates as fixed rates. In that case the corrector is second order only for the frozen-rate transport problem, not for the full nonlinear mizer dynamics.

See also

project_n