That seems to to allow for me to cook up a convergence test in terms of the 2 
norm.  What I’m really looking for is the ability to change things to be 
something like the 2 norm of the vector with elements

F_i/|x_i|

where I am looking for a root of F(x).  I can just build that scaling into the 
form function, but is there a way to do it without rewriting that piece of the 
code?


-gideon

> On Jan 12, 2016, at 12:14 AM, Barry Smith <[email protected]> wrote:
> 
> 
>   You can use SNESSetConvergenceTest() to use whatever test you want to 
> decide on convergence.
> 
> Barry
> 
>> On Jan 11, 2016, at 3:26 PM, Gideon Simpson <[email protected]> wrote:
>> 
>> I’m solving nonlinear problem for a complex valued function which is 
>> decomposed into real and imaginary parts, Q = u + i v.  What I’m finding is 
>> that where |Q| is small, the numerical phase errors tend to be larger.  I 
>> suspect this is because it’s using the 2-norm for convergence in the SNES, 
>> so, where the solution is already, the phase errors are seen as small too.  
>> Is there a way to use something more like an infinity norm with SNES, to get 
>> more point wise control?
>> 
>> -gideon
>> 
> 

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