[petsc-users] array and vec

陈乐平(Leping Chen) chenleping at yahoo.cn
Thu Apr 15 20:55:38 CDT 2010


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,  


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?



发件人: Matthew Knepley 
发送时间: 2010-04-16  22:48:18 
收件人: chenleping; PETSc users list 
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.




发件人: Jed Brown 
发送时间: 2010-04-16  21:21:47 
收件人: chenleping; PETSc users list 
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:

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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