ode.list.offOAT: Specify ODE equations for PWID off OAT
In HERU-LEM/LEMHIVpack: Localized Economic HIV Model

ode.list.offOAT Calculate the change of population in cells of PWID population but off OAT by the ODE model

ode.list.offOAT(
  x,
  x.oat,
  beta_o,
  beta_s,
  gamma,
  rho,
  ws,
  wp,
  mu_mat,
  mo,
  eta,
  psi,
  psi.p,
  theta.ai,
  theta.ad,
  phi,
  v2,
  v3,
  alpha,
  alpha.re,
  theta.1,
  theta.2,
  theta.t12,
  theta.t13,
  theta.t21,
  theta.t23,
  theta.t31,
  theta.t32,
  theta.t1O,
  theta.t2O,
  theta.t3O,
  oat.e,
  oat.q,
  rho.m
)

`x`	a vector containing the number of individuals off OAT x = c(S1,S2,Sp,Ia,I1,I2,I3,Iap,Ip,Da,D1,D2,D3,T1,T2,T3,O1,O2,O3)
`x.oat`	a vector containing the number of individuals on OAT
`rho`	the entry rate (assume the same for all groups)
`mu_mat`	maturation rates (age>65)
`mo`	mortality rates for 19 states
`eta`	PrEP entry rate
`psi`	screening rates for susceptible or infected
`psi.p`	screening rates for Iap (acute HIV on PrEP)
`theta.ai`	transition rate from acute states (Ia) to chronic state (CD4>=500; I1)
`theta.ad`	transition rate from acute states (Da) to chronic state (CD4>=500; D1)
`phi`	% infected of people receiving ART once diagnosed
`v2, v3`	symptom-based case finding rate for I2 and I3, respectively
`alpha`	ART initiation rate for D1,D2, and D3
`alpha.re`	ART re-initiation rate for o1,O2, and O3
`theta.1`	HIV disease progression rate for those not on ART, from I1/D1 to I2/D2
`theta.2`	HIV disease progression rate for those not on ART, from I2/D2 to I3/D3
`oat.e`	OAT entry rate
`oat.q`	OAT dropout rate
`lambda`	the sufficient contact rate
`lambda.p`	the sufficient contact rate for those on PrEP.
`1/ws`	average duration uninfected individuals in compartment S remain identified after screening
`1/wp`	average duration uninfected individuals in compartment Sp remain on PrEP
`psi.pr`	entry rate for PrEP
`theta.t`	transition probabilities for those on ART
`theta.o`	ART dropout probability from states T1,T2,T3