Re: [Libmesh-users] problem with inverse_map()

[Manav B. <bha...@gm...>]

As a followup, I have attached a screenshot of where the element in the error message is pointing. It is intriguing that the coordinates of all 4 nodes have virtually the same y-axis location (hence the hmin of 10^-11). I have circled the respective edge that these coordinates define. 

I should also note that I am using a custom function for flagging elements for refinement/coarsening. I have a scalar function define on the elements, and based on the value of the function I mark them for refinement or coarsening. So, this is a simple less-then/greater-than block. Not sure I am supposed to check for more parameters before flagging. 

Thanks,
Manav



> On May 1, 2019, at 5:25 PM, Manav Bhatia <bha...@gm...> wrote:
> 
> Hi, 
> 
>    I am using h-refinement in my analysis, which uses the mesh function routines to compute the value of the function in the interior of an element. 
> 
>    All of my elements in the original mesh (before any refinements) are squares (quad4). 
> 
>    For the most part everything works out fine without any issues. Occasionally, however, I will get an error in the inverse_map() like this. I am particularly perplexed by the hmin() size of 10^-11. 
> 
>    The size of my elements before refinement is hmin() = .015 and I allow a max of 4 refinements in any element. Would there be any reason to expect an hmin of order 10^-11 in this case? 
> 
> Thanks,
> Manav
> 
> 
> WARNING: At least one element took more than 10 iterations to converge in inverse_map()...
> Rerun in devel/dbg mode for more details.
> ERROR: Newton scheme FAILED to converge in 21 iterations in element 16514 for physical point = (x,y,z)=(    0.27,   0.2775,        0)
>   Elem Information
>    id()=16514, processor_id()=2
>    type()=QUAD4
>    dim()=2
>    n_nodes()=4
>     0  Node id()=13234, processor_id()=4294967295, Point=(x,y,z)=(    0.27,   0.2775,        0)
>     DoFs=
>     1  Node id()=604, processor_id()=2, Point=(x,y,z)=(0.271875,   0.2775,        0)
>     DoFs=(0/0/13470) (0/1/13471) (0/2/13472) (0/3/13473) (0/4/13474) (0/5/13475) (2/0/2245) (3/0/2245) 
>     2  Node id()=13235, processor_id()=4294967295, Point=(x,y,z)=(0.271875,   0.2775,        0)
>     DoFs=
>     3  Node id()=13233, processor_id()=4294967295, Point=(x,y,z)=(    0.27,   0.2775,        0)
>     DoFs=
>    n_sides()=4
>     neighbor(0)=nullptr
>     neighbor(1)=nullptr
>     neighbor(2)=nullptr
>     neighbor(3)=nullptr
>    hmin()=9.89829e-11, hmax()=0.001875
>    volume()=1.85593e-13
>    active()=1, ancestor()=0, subactive()=0, has_children()=0
>    parent()=672
>    level()=4, p_level()=0
>    refinement_flag()=DO_NOTHING
>    p_refinement_flag()=DO_NOTHING
>    DoFs=
> Exiting...
> [2] src/fe/fe_map.C, line 1905, compiled Apr 20 2019 at 20:02:41
>