update_body_composition: Update body composition during simulation (Mid-level)

In fb4package: 'Fish Bioenergetics 4.0' Model Implementation with High-Performance 'TMB' Backend

Update body composition during simulation (Mid-level)

Description

Updates body composition as fish grows or changes condition Used during simulation loops - assumes pre-validated inputs

Usage

update_body_composition(
  old_weight,
  new_weight,
  old_composition = NULL,
  processed_composition_params
)

Arguments

old_weight	Previous weight (g)
new_weight	New weight (g)
old_composition	Previous composition (optional)
processed_composition_params	List with processed composition parameters

Value

A named list with the same 13 elements as calculate_body_composition, describing the body composition at new_weight. If old_composition is supplied, an additional element changes is appended — a named list with five numeric scalars: weight_change, water_change, protein_change, fat_change, and energy_density_change (all in the same units as the corresponding composition elements).

Examples

params <- list(water_fraction = 0.72, fat_energy = 36450,
               protein_energy = 17990, max_fat_fraction = 0.30)
old <- calculate_body_composition(weight = 100,
                                  processed_composition_params = params)
update_body_composition(old_weight = 100, new_weight = 110,
                        old_composition = old,
                        processed_composition_params = params)

fb4package documentation built on May 8, 2026, 1:07 a.m.