%let n=10000;

data t1;
   do i=1 to &n;
      x=rannor(123);
      y=1+1*x+rannor(123);
      x0=1;
      output;
    end;
    keep y x x0;
run;


proc nlmixed data=t1;
parms b0 b1=0 s=2;
e=y-(b0 + b1*x);
*loglik=log(pdf('normal',e,0,s));
loglik=log( ( 1/(s*sqrt(2*constant('pi')))) * exp(  -(y - (b0 + b1*x))**2/(2*s**2)) );
model y ~ general (loglik);
run;

proc optmodel;
   set I = 1 .. &n;
   number y{I};
   number x{I};
   read data t1 into [_n_] y x ;
   var b0 init 0, b1 init 0, s init 2;
   impvar loglik=sum{k in I}
         -2*log( ( 1/(s*sqrt(2*constant('pi')))) * exp(  -(y[k]- (b0 + b1*x[k]))**2/(2*s**2)) );

/*          -2*log(pdf('normal', y[k] - (b0 + b1*x[k]))); */
   min f = loglik;
    reset printlevel=2;  
   solve with nlp / hesstype=full;
   print  b0 b1 s;
quit;