Build an AFNI-style restricted AR plan from root parameters

Usage

afni_restricted_plan(
  resid,
  runs = NULL,
  parcels = NULL,
  p = 3L,
  roots,
  estimate_ma1 = TRUE,
  exact_first = TRUE
)

resid: (n x v) residual matrix (used only if estimate_ma1=TRUE)
runs: integer vector length n (optional)
parcels: integer vector length v (optional; if provided, plan pooling='parcel')
p: either 3 or 5
roots: either a single list with elements named as needed - for p=3: list(a, r1, t1, vrt = 1.0) - for p=5: list(a, r1, t1, r2, t2, vrt = 1.0) or a named list of such lists keyed by parcel id (character) for per-parcel specs. As in AFNI, a, r1, r2 must be non-negative (values above 0.95 are clamped to 0.95) and angles are clamped to [0, pi]. vrt is AFNI's signal-to-total variance ratio s^2 / (s^2 + w^2) for additive white noise w; it is used when estimate_ma1 = FALSE.
estimate_ma1: logical. If TRUE, estimate an MA(1) term from the AR-filtered voxels to stand in for AFNI's additive white noise (vrt is then ignored). If FALSE, the white-noise share is taken from vrt: for vrt < 1 the plan is the exact ARMA(p, p) equivalent of AR(p) plus white noise, so its autocorrelation is vrt times the AR autocorrelation at every non-zero lag; vrt = 1 (default) gives the pure AR(p).
exact_first: apply exact AR(1) scaling at segment starts (harmless here; default TRUE)

An fmriAR_plan with method = "afni" that can be supplied to whiten_apply().

NULL
#> NULL