dolfin team mailing list archive

[A Navaei <axnavaei@xxxxxxxxxxxxxx>]

2009/2/19 Anders Logg <logg@xxxxxxxxx>:
> On Thu, Feb 19, 2009 at 02:53:52PM +0000, A Navaei wrote:
>> ---------- Forwarded message ----------
>> From: A Navaei <axnavaei@xxxxxxxxxxxxxx>
>> Date: 2009/2/19
>> Subject: Re: [DOLFIN-dev] A minimal c++ Function test and some bugs
>> To: Johan Hake <hake@xxxxxxxxx>
>>
>>
>> 2009/2/19 Johan Hake <hake@xxxxxxxxx>:
>> > On Thursday 19 February 2009 14:54:57 A Navaei wrote:
>> >> 2009/2/19 Johan Hake <hake@xxxxxxxxx>:
>> >> > On Thursday 19 February 2009 14:46:18 A Navaei wrote:
>> >> >> 2009/2/19 Garth N. Wells <gnw20@xxxxxxxxx>:
>> >> >> > A Navaei wrote:
>> >> >> >> 2009/2/19 Johan Hake <hake@xxxxxxxxx>:
>> >> >> >>> The previous email was sent a bit premature...
>> >> >> >>>
>> >> >> >>> [snip]
>> >> >> >>>
>> >> >> >>>>> I have also thought of this :)
>> >> >> >>>>>
>> >> >> >>>>> Then you can take an ordered mesh, iterate over the vertices, and
>> >> >> >>>>> use the
>> >> >> >>>>> present implementation of the eval function (which in its present
>> >> >> >>>>> shape is a piecewise constant interpolator isn't it?), to fill the
>> >> >> >>>>> new _vector,
>> >> >> >>>>> all done in the constructor. Then you have a discrete function in
>> >> >> >>>>> the first place :)
>> >> >> >>>>
>> >> >> >>>> Is it possible to set the pointer to _vector data directly where we
>> >> >> >>>> can pass the pointer to image data? If this works, no loop will be
>> >> >> >>>> involve in data conversion and it will be super fast.
>> >> >> >>>
>> >> >> >>> Yes but you do not know how the mesh is ordered.
>> >> >> >>
>> >> >> >> Consider a 2D image data mapped on a structured grid, with size
>> >> >> >> (number of nodes in each direction) of (sx, sy), the value of image
>> >> >> >> brightness at coordinate (i, j) is given by I(k), where:
>> >> >> >>
>> >> >> >> k = i + sx * j
>> >> >> >>
>> >> >> >> Is this not enough information to create the mesh?
>> >> >> >>
>> >> >> >>>> It seems _vector.set()
>> >> >> >>>>
>> >> >> >>>> (http://www.fenics.org/pub/documents/dolfin/dolfin-progr-reference/
>> >> >> >>>>d6/ da4/c
>> >> >> >>>> lassdolfin_1_1GenericVector.html#bc4ecede55f2846ecadae02426df8f63)
>> >> >> >>>> accepts
>> >> >> >>>> the pointer to each row, is that right?
>> >> >> >>>
>> >> >> >>> There is no such thing as a row in a vector. It stores the data in a
>> >> >> >>> contigouos way (if not distributed).
>> >> >> >>
>> >> >> >> No idea why it says rows: virtual void dolfin::GenericVector::set
>> >> >> >> (const double *block, const uint *num_rows, const uint *const *
>> >> >> >>        rows).
>> >> >> >
>> >> >> > You can set as few or as many entries as you wish at once. 'block'
>> >> >> > contains the values you want to set, 'num_rows' are the number of
>> >> >> > entries you wish to set, and 'rows' are the positions into which the
>> >> >> > entries should be inserted.
>> >> >>
>> >> >> I hate to say this, but _vector is private!
>> >> >
>> >> > ... and perfectly accesable through vector()
>> >>
>> >> ... and perfectly read-only through vector()
>> >
>> > I past from Function.h
>> >
>> >    /// Return the vector of expansion coefficients, automatically
>> >    /// initialized to zero if coefficients have not been computed (non-const
>> > version)
>> >    GenericVector& vector();
>> >
>> >    /// Return the vector of expansion coefficients, automatically
>> >    /// initialized to zero if coefficients have not been computed (const
>> > version)
>> >    const GenericVector& vector() const;
>> >
>> > So one const version and one that is not.
>>
>> Would this be the right way of initialising _vector in the subclass? :
>>
>>      DefaultFactory factory;
>>      vector() = *(boost::shared_ptr<GenericVector>(factory.create_vector()));
>>
>> Try attached in your sandbox.
>
> No, just do
>
>  vector();
>
> That will initialize a zero vector of correct size.

These two work:

  Function1(boost::shared_ptr<const Image> image) : Function()
  {
  };

  Function1() : Function()
  {
    vector();
  };

But the combination generates a segmentation fault:

class Function2 : public Function
{
public:
  Function2(boost::shared_ptr<const Image> image) : Function()
  {
    vector();
  };
};

The trace includes /libdolfin.so.0(_ZN6dolfin8Function6vectorEv+0x38).
Example attached.


-Ali


>
> --
> Anders
>

[snip]

// Place for random tests

#include <dolfin.h>

using namespace dolfin;

class Image
{
public:

  Image()
  {
  };
};

class Function1 : public Function
{
public:
  Function1(boost::shared_ptr<const Image> image) : Function()
  {
  };
  
  Function1() : Function()
  {
    vector();
  };
};

class Function2 : public Function
{
public:
  Function2(boost::shared_ptr<const Image> image) : Function()
  {
    vector();
  };
};

int main()
{  
  boost::shared_ptr<Image> image(new Image());
  
  Function1 v1();
  message("[debug] 0");
  
  Function1 v2(image);
  message("[debug] 1");
  
  Function2 v3(image);
  message("[debug] 2");
}