fit_td_fallback: Fit a self-start model with time-delay fallback

In mnirs: Muscle Near-Infrared Spectroscopy Processing and Analysis

Fit a self-start model with time-delay fallback

Description

Shared attempt skeleton for the nls-based kinetics workers. The TD model is flat at A before TD, so the pre-onset baseline anchors A; the reduced model has no such region and diverges at t < 0, so it is fit from start_time onward. An under-determined attempt is rejected before it reaches fitter, and a failed TD fit falls back to the reduced model without TD unless TD is user-fixed. Every failure is reported through warn_fit_failed().

Usage

fit_td_fallback(x_fit, t_fit, params, .a, fitter, fn, ctx)

Arguments

x_fit, t_fit	Numeric vectors of the channel fit window.
params	Character vector of parameter names in model order, including TD when the channel fits the TD model.
.a	The channel's resolved argument list (use_TD, fix).
fitter	A function ⁠(.data, .params, on_error)⁠ fitting .params to a data frame with the response and time columns named per fit_names() and returning an nls model or NULL. on_error(e) reports the condition e and returns NULL, so it doubles as a tryCatch() error handler.
fn	Symbol; the self-start fn named in the warning.
ctx	The channel context list of analyse_kinetics_channels().

Value

A list with model (or NULL), the params actually fit, the logical row filter keep, and the fit data frame.

mnirs documentation built on Sept. 13, 2026, 1:06 a.m.