[petsc-users] *****SPAM*****Create vector with evenly spaced values

[Jed Brown]

Florian Lindner <mailinglists at xgm.de> writes:

> Am Freitag, 29. August 2014, 09:29:21 schrieben Sie:
>> Florian :
>> >>
>> >> is there a way to create a vector with evenly spaced values in an
>> >> interval, like the numpy.arange function?
>> >> http://docs.scipy.org/doc/numpy/reference/generated/numpy.arange.html
>> >> or the linspace function?
>> >
>> >
>> > Ok, I gave it as try. Do I need the VecAssembly the vector?
>> 
>> No, but you need VecResetArray() when vector is no longer used.
>
> Why do I need to call that if I have no intention going back to the original values? Of course I do VecDestroy the vector?

Then your use of VecReplaceArray is really weird.  Get rid of the malloc
and use VecGetArray, set the values, then VecRestoreArray.

>> > void arange(size_t start, size_t stop)
>> >     {
>> >       // given a vector of appropriate size
>> >       PetscScalar ierr;
>> >       PetscScalar *a;
>> >       ierr = PetscMalloc(sizeof(PetscScalar) * (stop-start), &a);
>> > CHKERRV(ierr);
>> >       size_t pos = 0;
>> >       for (size_t i = start; i < stop; i++) {
>> >         a[pos] = i;
>> >         pos++;
>> >       }
>> >       cout << "Array filled." << endl;
>> >       VecReplaceArray(vector, a);
>> >       // VecAssemblyBegin(vector); VecAssemblyEnd(vector);  Do I need that?
>> >     }
>> >
>> > Any comments?
>> >
>> > Thanks,
>> > Florian
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