Hi everyone,
Could you please assist me? When trying to model complex absorption with inverse Gaussian functions, I keep getting this error message "Model execution failed. Initial parameter values result in -LL = NaN" I have tried different initial estimates for MAT and CV without success.
See below the model code:
test(){
input = t ==0 ? 0 : ((MAT/(6.283*CV^2*t^3))^0.5) *exp(-((MAT-t)^2)/(2*CV^2*MAT*t))
P1 = (MAT/(2*3.14*CV*CV*(t+0.000001)**3))
P2 = P1**0.5
P3 = (MAT-(t+0.000001))*(MAT-(t+0.000001))/(2*CV*CV*MAT*(t+0.000001))
IG = 1*P2*exp(-P3)
deriv(Aa = -input * Aa)
deriv(A1 = input * Aa - Cl * C- Cl2 * (C - C2))
deriv(cumabs = IG )
#deriv(Aa = - Ka * Aa)
#deriv(A1 = Ka * Aa - Cl * C - Cl2 * (C - C2))
deriv(A2 = Cl2 * (C - C2))
dosepoint(Aa)
C = A1 / V
cumabsout = cumabs
C2 = A2 / V2
error(CEps = 0.171872765515157)
observe(CObs = C * (1 + CEps))
#stparm(Ka = tvKa * exp(nKa))
stparm(MAT = tvMAT * exp(nMAT))
stparm(CV = tvCV * exp(nCV))
stparm(V = tvV * exp(nV))
stparm(V2 = tvV2)
stparm(Cl = tvCl * exp(nCl))
stparm(Cl2 = tvCl2 * exp(nCl2))
fixef(tvMAT = c(,5,))
fixef(tvCV = c(,0.6,))
#fixef(tvKa = c(, 12.5738819057084, ))
fixef(tvV = c(, 43.2890620436938, ))
fixef(tvV2 = c(, 45.1186153287527, ))
fixef(tvCl = c(, 7.49094934958544, ))
fixef(tvCl2 = c(, 154.794695950696, ))
ranef(diag(nV, nCl, nMAT, nCV, nCl2) = c(0.49173913, 0.71344537, 0.001, 0.001, 0.38537209))
}
Many thanks and kind regards,
Ahmed