[Developers] fixing init_number_vector without a plan

[dave fournier]

On 12-04-04 07:28 PM, Johnoel Ancheta wrote:

Well it needs more work first. I just wanted to illustrate an approach.


> Geez, that is cool.  Thanks Dave, this is a great way to do code
> testing.  I'll work on this tomorrow or you can commit the fix.
>
> Johnoel
>
> On Wed, Apr 4, 2012 at 2:14 PM, dave fournier <davef at otter-rsch.com 
> <mailto:davef at otter-rsch.com>> wrote:
>
>
>     At our workshop Mark pointed out some problem with the
>     init_number_vector class for RE models.
>     I have identified some serious problems that are not so easy to
>     fix so I wondered if, as an exercise
>     it would be easy to use some C++ capabilities to introduce a new
>     class which works better,
>     without having to modify the existing code.  This sort of
>     programming typically uses virtual
>     functions.
>
>     One starts with the  df1b2_init_vector class which is what gets
>     invoked when you use an init_vector
>     in an RE model. Now the problem with a df1b2_init_vector is that
>     it only
>     has an int for its starting phase.  Since we want the different
>     elements
>     of the vector to have their own starting phase we will add that to
>     the class.
>     Sow we derive a new   class xdf1b2_init_number_vector from
>     public df1b2_init_vector and add what we need to it.
>
>     class xdf1b2_init_number_vector : public df1b2_init_vector
>     {
>        index_type * it;
>
>       // ... other stuff
>
>     };
>
>     all that is needed is a pointer to index_type.  This will permit
>     the use
>     of a vector or a number to specify the starting phases. If a
>     number is used
>     they will all be the same.
>
>     Now what you can do is to use the class in a toy program.
>     Start with a tpl file like this.
>     ********************************************************
>     ********************************************************
>
>     DATA_SECTION
>      int n
>      !! n=2;
>      ivector st(1,n)
>      !! st(1)=1;
>      !! st(2)=-1;
>
>
>     PARAMETER_SECTION
>      init_number_vector beta(1,n,st)
>      random_effects_vector eps(1,1)
>
>      objective_function_value f
>
>     PROCEDURE_SECTION
>      f+=0.5*norm2(eps);
>      for (int i=1;i<=n;i++)
>      {
>        f+= square(beta(i)-1.0);
>      }
>
>     GLOBALS_SECTION
>
>
>     #include <admodel.h>
>      #include <df1b2fun.h>
>      #include <adrndeff.h>
>      class xdf1b2_init_number_vector : public df1b2_init_vector
>      {
>        index_type * it;
>      public:
>        xdf1b2_init_number_vector(void);
>
>        void allocate(int imin,int imax,const index_type& ps,char * s)
>        {
>          df1b2_init_vector::allocate(imin,imax,s);
>          it=new index_type(ps);
>        }
>
>      };
>
>      xdf1b2_init_number_vector::xdf1b2_init_number_vector(void):
>        df1b2_init_vector()
>      {
>        it=0;
>      }
>
>     ********************************************************
>     ********************************************************
>     ********************************************************
>     ********************************************************
>
>     Run tpl2rem on this tpl file and change
>
>      df1b2_init_number_vector  to  xdf1b2_init_number_vector
>
>     in the cpp and htp files and compile with debug and safe mode.
>     When you run the model you will ifnd that it runs out of an array
>     in
>        void df1b2_init_vector set_value(const init_df1b2vector&
>     _x,const int& _ii,
>          const df1b2variable& pen);
>
>     The reason is that it is using the starting phase number from that
>     class.
>     To change that behaviour we just need override the set_value function
>     with a new one in the derived class. It looks like this.
>
>
>
>      void xdf1b2_init_number_vector::set_value(const init_df1b2vector& x,
>        const int& _ii,const df1b2variable& pen)
>      {
>        ADUNCONST(int,ii)
>        int mmin=indexmin();
>        int mmax=indexmax();
>        for (int i=mmin;i<=mmax;i++)
>        {
>          if (withinbound(0,ad_integer((*it)(i)),current_phase))
>            (*this)(i) = (x(ii++));
>        }
>      }
>
>     The change is
>
>      if (withinbound(0,ad_integer((*it)(i)),current_phase)
>
>     which has been added to the function.
>     The class declaration is extended to
>
>      class xdf1b2_init_number_vector : public df1b2_init_vector
>      {
>        index_type * it;
>      public:
>        xdf1b2_init_number_vector(void);
>
>        void allocate(int imin,int imax,const index_type& ps,char * s)
>        {
>          df1b2_init_vector::allocate(imin,imax,s);
>          it=new index_type(ps);
>        }
>        virtual void set_value(const init_df1b2vector& _x,const int& _ii,
>          const df1b2variable& pen);
>      };
>
>     It seems to work, although there may be some other functions which
>     will need
>     to be overridden as well.
>
>     What's my point?  Well no planning or committees were needed. All
>     I had
>     to do was to run the code with the debugger and it told me what to
>     do. Entire
>     process took about two hours.
>
>     Time for a drink.
>
>
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>

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