pdr_cost {PoolDilutionR}

Cost function between observed and predicted pools

Description

Cost function between observed and predicted pools

Usage

pdr_cost(
  params,
  time,
  m,
  n,
  m_prec,
  ap_prec,
  P,
  k,
  pool = "CH4",
  frac_P = frac_P_default(pool),
  frac_k = frac_k_default(pool),
  log_progress = NULL
)

Arguments

params

Named list holding optimizer-assigned values for parameters

time

Vector of numeric time values; first should be zero

m

Observed total pool size, same length as time

n

Observed pool size of heavy isotope, same length as time

m_prec

Instrument precision for pool size, expressed as a standard deviation

ap_prec

Instrument precision for atom percent, expressed as a standard deviation

P

production rate, unit pool size/unit time

k

first-order rate constant for consumption, 1/unit time

pool

Name of pool; see pdr_fractionation

frac_P

Fractionation value for production; see pdr_fractionation

frac_k

Fractionation value for consumption; see pdr_fractionation

log_progress

An optional logging function

Value

Returns a cost metric summarizing the difference between the predicted and observed m (total pool size) and AP (atom percent).

Note

This implements Equations 12-14 from von Fischer and Hedin (2002).

Author(s)

K.A. Morris & B. Bond-Lamberty

Examples

m <- c(10, 8, 6, 5, 4, 3)
n <- c(1, 0.7, 0.6, 0.4, 0.3, 0.2)
pdr_cost(params = list(P = 0.5, k = 0.3), time = 0:5, m, n, m_prec = 0.001, ap_prec = 0.01)