[petsc-users] array and vec

[陈乐平（Leping Chen）]

thanks,

but I don't understand VecGetArray(), that is to say, I don't know how to call VecGetArray() 

when I plan to get any local values of x,  

Maybe,

double precision u(n)

Vec x

PetscOffset uu_i

call VecGetArray(x,u,uu_i,ierr)

is it right? 

it seems don't work. how can I call it?

thanks,

leping



发件人： Matthew Knepley 
发送时间： 2010-04-16  22:48:18 
收件人： chenleping; PETSc users list 
抄送： 
主题： Re: [petsc-users] array and vec 
 
2010/4/15 陈乐平（Leping Chen） <chenleping at yahoo.cn>

hello, petsc teams,

when I use FormFuncion(), I need use a value of x;

but x is defined by Vec, I don't know how to get  a value of x, for example, the 3rd value.


Exactly as Jed wrote, you can use VecGetArray() to access any local values
of x.


   Matt


thanks,

leping
  



发件人： Jed Brown 
发送时间： 2010-04-16  21:21:47 
收件人： chenleping; PETSc users list 
抄送： 
主题： Re: [petsc-users] array and vec 
On Thu, 15 Apr 2010 21:17:19 +0800, "=?gb2312?B?s8LA1sa9?=" <chenleping at yahoo.cn> wrote:
> petsc teams,
> 
> for following definitions:
> 
> double precision u(n)
> Vec  v
> 
> then, how can I actualize mutual updating between u(n) and v?
I'm not sure what you mean, if these are the same quantity then they
shouldn't be stored in separate locations.  See VecGetArray:
  http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Vec/VecGetArray.html
Jed



-- 
What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
-- Norbert Wiener
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