ef_fun
returns amount of vehicles at each age
Numeric; numeric vector of emission factors.
Character; "logistic" by default so far.
Numeric; vector for ages of use.
Numeric; the x-value of the sigmoid's midpoint,
Numeric; the steepness of the curve.
Integer; the curve's maximum value.
Logical; to show the equation.
numeric vector.
https://en.wikipedia.org/wiki/Logistic_function
if (FALSE) {
CO <- ef_cetesb(p = "CO", veh = "PC_G")
ef_logit <- ef_fun(ef = CO, x0 = 27, k = 0.4, L = max(CO))
df <- data.frame(CO, ef_logit)
colplot(df)
}