OK. I see. Thanks, John.

On Mon, Jul 18, 2016 at 1:55 PM, John Peterson <jwpeter...@gmail.com> wrote:

>
>
> On Mon, Jul 18, 2016 at 12:42 PM, Xujun Zhao <xzha...@gmail.com> wrote:
>
>> It sounds like this is an inherent problem of the present algorithm for
>> determining if a point is in an element??? especially for complex elements
>> such as HEX27.
>>
>
> It's only a problem because we aren't properly handling the failure
> case...  We know that points will sometimes be outside elements, we just
> need the inverse_map function to not throw an error in such a case.
>
>
>
>> Is there any other more robust solution in computational geometry?
>>
>
> For that element, I doubt it, however, we accept pull requests.
>
>
>
>> I also tried to use the 1st order element, it passed the test for this
>> simple case, although I am not sure if this really solves the problem. Is
>> it possible to add another contains_point(Point& pt, ORDER order) that
>> allows using lower order shape function? In CFD with mixed finite elements,
>> we sometimes use higher order interpolation for velocity and lower order
>> ones for pressure. But when to determine which element a point moves into,
>> we can still use first order algorithm as an approximation.
>>
>
>
>
>
> Also, how about the tri/tet elements? Will they cause zero determinant
>> problems?
>
>
> The lower order ones (TRI3 and TET4) have contains_point()
> specializations, but I see that the Tet4 one also needs a similar try/catch
> block fix since it uses TypeTensor::solve().
>
> --
> John
>
>
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