[ADMB Users] spline

[Luis Ridao]

ADMB-help,

Following suggestions proposed to my initial request I have modified the code:

DATA_SECTION
....
 init_vector LO(1,nNodes)// SPLINES
 init_vector HI(1,nNodes)
 init_ivector PH(1,nNodes)
 init_vector parm(1,2)

PARAMETER_SECTION
.....
 init_bounded_number_vector log_sel1(1,nNodes,LO,HI,PH)
// SPLINES
 init_bounded_number_vector log_sel2(1,nNodes,LO,HI,PH)
// SPLINES
 init_bounded_number_vector log_sel3(1,nNodes,LO,HI,PH)
// SPLINES
 vector predSel1(1,nages)      // SPLINES
 vector predSel2(1,nages)      // SPLINES
 vector predSel3(1,nages)      // SPLINES

PROCEDURE_SECTION
......
 for (i=1;i<=nyrs;i++)
 {
 if (i<=16)
 {
   vcubic_spline_function qs(nodes,log_sel1,parm(1),parm(2));   // SPLINES
   predSel1.sub(1,9)=qs(ages.sub(1,9));
   predSel1(10)=0;
   predSel1(11)=0;
   predSel1(12)=0;

 }
 else
 {
 if (i<=35)
 {
   vcubic_spline_function qs(nodes,log_sel2,parm(1),parm(2));   // SPLINES
   predSel2.sub(1,9)=qs(ages.sub(1,9));
   predSel2(10)=0;
   predSel2(11)=0;
   predSel2(12)=0;
......
......

And the .dat file looks like:
....
.....
# selection Nodes
 6
# node info
 -15 -15 -15 -15 -15 -15                # lower bound
 15  15  15  15  15  15                # upper bound
  2   2   2   2   2   2                # phase

# derivative at first and last nodes
  0  0


I have run the model with different knots and it works when they are
set to 4, 5, 6, 8 or 9
BUT not for 7 ("Hessian does not appear to be positive definite")
I'm happy with 6 knots (the AIC is lowest for this value)
but I was just wondering why this issue keeps coming up.

The code is attached,
best,
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