Re: [petsc-users] Question about NASM initialization

[Takahashi, Tadanaga]

Ok, thanks for the clarification.

On Thu, Apr 6, 2023 at 10:25 AM Matthew Knepley  wrote:

> On Thu, Apr 6, 2023 at 10:21 AM Takahashi, Tadanaga  wrote:
>
>> I am following up from the last inquiry. I read the source code nasm.c
>>  and it looks
>> like sub-snes iteration is being initialized with a scatter call from the
>> previous solution. In other words, if I use Newton's method for the local
>> solver, then in each NASM iteration the Newton's method uses the previous
>> local solution as the initial guess. Can anyone confirm this?
>>
>
> This is the intention. There are not many tests, so it is possible there
> is a bug, but it is supposed to use the existing solution.
>
>   Thanks,
>
> Matt
>
>
>> On Sun, Apr 2, 2023 at 6:14 PM Takahashi, Tadanaga  wrote:
>>
>>> Hello PETSc devs,
>>>
>>> I am using SNES NASM with Newton LS on the sub-SNES. I was wondering how
>>> the sub-SNES chooses the initial guess during each NASM iteration. Is it
>>> using the previously computed solution or is it restarting from zero?
>>>
>>
>
> --
> 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
>
> https://www.cse.buffalo.edu/~knepley/
> 
>

Re: [petsc-users] Question about NASM initialization

[Matthew Knepley]

On Thu, Apr 6, 2023 at 10:21 AM Takahashi, Tadanaga  wrote:

> I am following up from the last inquiry. I read the source code nasm.c
>  and it looks
> like sub-snes iteration is being initialized with a scatter call from the
> previous solution. In other words, if I use Newton's method for the local
> solver, then in each NASM iteration the Newton's method uses the previous
> local solution as the initial guess. Can anyone confirm this?
>

This is the intention. There are not many tests, so it is possible there is
a bug, but it is supposed to use the existing solution.

  Thanks,

Matt


> On Sun, Apr 2, 2023 at 6:14 PM Takahashi, Tadanaga  wrote:
>
>> Hello PETSc devs,
>>
>> I am using SNES NASM with Newton LS on the sub-SNES. I was wondering how
>> the sub-SNES chooses the initial guess during each NASM iteration. Is it
>> using the previously computed solution or is it restarting from zero?
>>
>

-- 
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

https://www.cse.buffalo.edu/~knepley/ 

Re: [petsc-users] Question about NASM initialization

[Takahashi, Tadanaga]

I am following up from the last inquiry. I read the source code nasm.c
 and it looks
like sub-snes iteration is being initialized with a scatter call from the
previous solution. In other words, if I use Newton's method for the local
solver, then in each NASM iteration the Newton's method uses the previous
local solution as the initial guess. Can anyone confirm this?

On Sun, Apr 2, 2023 at 6:14 PM Takahashi, Tadanaga  wrote:

> Hello PETSc devs,
>
> I am using SNES NASM with Newton LS on the sub-SNES. I was wondering how
> the sub-SNES chooses the initial guess during each NASM iteration. Is it
> using the previously computed solution or is it restarting from zero?
>

[petsc-users] Question about NASM initialization

[Takahashi, Tadanaga]

Hello PETSc devs,

I am using SNES NASM with Newton LS on the sub-SNES. I was wondering how
the sub-SNES chooses the initial guess during each NASM iteration. Is it
using the previously computed solution or is it restarting from zero?