[Insight-users] RegularStepGradientDescentBaseOptimizer

[Bing Jian]

-- 
Best wishes,
Bing Jian
bjian at cise . ufl . edu


On Tue, 11 Nov 2003, Luis Ibanez wrote:

> Hi Bing,
>
> The method GetScales() is defined in the Superclass.
>
> Whenever you have doubts regarding the location of
> methods in the superclasses, simply follow the
> Doxygen page. For example, look at the UML class
> diagram in:
>
> http://www . itk . org/Insight/Doxygen/html/classitk_1_1RegularStepGradientDescentOptimizer . html
>
> That will bring you rapidly to find the method GetScales()
> implemented at the level of
>
> http://www . itk . org/Insight/Doxygen/html/classitk_1_1Optimizer . html

  I got it. It's declared as
  itkGetConstReferenceMacro( Scales, ScalesType );

  I only searched GetScales(). Forgot the macro. My bad.

>
>
> 2) In what circumstances did you find the value of the
>     scale[] components to be Null ?
>
>     That will break the behavior of the compiler....
>
>     You must set the scaling array before starting
>     the optimization (the registration for that matter).
>

      Do you mean it's registation's responsibility to set the
  scaling array of optimizer? How to do it? maybe I missed some
  statement in  example programs.

      Thanks!


>     Zero is not an acceptable value for the scaling
>     factors.
>
>
>
> Regards,
>
>
>    Luis
>
>
> =-----------------------------
> Bing Jian wrote:
> > Hi, Luis,
> >
> > In \Code\Numerics\itkRegularStepGradientDescentBase.cxx,
> > You have following function:
> >
> > /**
> >  * Advance one Step following the gradient direction
> >  */
> > void
> > RegularStepGradientDescentBaseOptimizer
> > ::AdvanceOneStep( void )
> > {
> >    //...
> >    ScalesType     scales = this->GetScales();
> >   for(unsigned int i = 0;  i < spaceDimension; i++)
> >     {
> >     transformedGradient[i]  = m_Gradient[i] / scales[i];
> >     previousTransformedGradient[i] =
> >       m_PreviousGradient[i] / scales[i];
> >     }
> >    //...
> > }
> >
> > Regarding the code above, I have two questions:
> > 1) where is the definition of GetScales()? I cannot find it.
> > 2) In my debugging, I did find scales[i] == 0 at some points.
> >    I guess this case should be taken care of.
> >
> > Thanks!
> >
>
>
>
>
>