clear all
use accident3
local depvar    "accidents"
local indepvars "cvalue ibn.kids traffic"
_rmcoll `indepvars', expand
local cnames "`r(varlist)' _cons"
local p   : word count `cnames'
matrix bt = J(1, `p', 0)
matrix colnames bt = `cnames'
_ms_omit_info bt
matrix bto = r(omit)

mata:
void plleval3(real scalar todo, real vector b,     ///
              real vector y,    real matrix X,     ///
	      val, grad, hess)
{
    real vector  xb

    xb = X*b'
   val = -exp(xb) + y:*xb - lnfactorial(y)
}

y  = st_data(., "`depvar'")
X  = st_data(., "`indepvars'")
X  = X,J(rows(X), 1, 1)

mo = st_matrix("bto")
ko = sum(mo)
p  = cols(mo)
if (ko>0) {
    Ct   = J(0, p, .)
    for(j=1; j<=p; j++) {
        if (mo[j]==1) {
            Ct  = Ct \ e(j, p)
        }
    }
    Ct = Ct, J(ko, 1, 0)
}
else {
    Ct = J(0,p+1,.)
}

S  = optimize_init()
optimize_init_argument(S, 1, y)
optimize_init_argument(S, 2, X)
optimize_init_evaluator(S, &plleval3())
optimize_init_evaluatortype(S, "gf0")
optimize_init_params(S, J(1, 7, .01))
optimize_init_constraints(S, Ct)

bh = optimize(S)
optimize_result_params(S)
end