# Latest **URL:** https://bempp.discourse.group/latest.md?page=3 [Latest](https://bempp.discourse.group/latest.md) · [Categories](https://bempp.discourse.group/categories.md) **Page:** 4 --- ## [Function for spatial derivative of the potential field](https://bempp.discourse.group/t/function-for-spatial-derivative-of-the-potential-field/134)
**Author:** [@mospel](https://bempp.discourse.group/u/mospel)\ **Replies:** 1\ **Last updated:** [29 April 2022 12:39 UTC](https://bempp.discourse.group/t/function-for-spatial-derivative-of-the-potential-field/134 "2022-04-29T12:39:52Z")
Are there functions in BEMPP to calculate the spatial gradient of the potential in a grid function? --- ## [Define the source point in the electromagnetic](https://bempp.discourse.group/t/define-the-source-point-in-the-electromagnetic/132)
**Author:** [@changyan](https://bempp.discourse.group/u/changyan)\ **Replies:** 1\ **Last updated:** [6 April 2022 16:23 UTC](https://bempp.discourse.group/t/define-the-source-point-in-the-electromagnetic/132 "2022-04-06T16:23:20Z")
Greetings everyone, I am studying the electromagnetic scattering problem by BEMPP and have seen the example ‘‘Bistatic RSC generated by dielectric spheres’’. Notice that the incident field is given in the form of the pl… --- ## [AttributeError: '\_ProductDiscreteOperator' object has no attribute 'is\_barycentric'](https://bempp.discourse.group/t/attributeerror-productdiscreteoperator-object-has-no-attribute-is-barycentric/130)
**Author:** [@Gustavo](https://bempp.discourse.group/u/Gustavo)\ **Replies:** 1\ **Last updated:** [28 March 2022 11:51 UTC](https://bempp.discourse.group/t/attributeerror-productdiscreteoperator-object-has-no-attribute-is-barycentric/130 "2022-03-28T11:51:46Z")
Hi, This I’m having this error message AttributeError: '\_ProductDiscreteOperator' object has no attribute 'is\_barycentric'on the following piece of code: identity = bempp.api.operators.boundary.sparse.identity(space, s… --- ## [Problems using NtD operator](https://bempp.discourse.group/t/problems-using-ntd-operator/128)
**Author:** [@Gustavo](https://bempp.discourse.group/u/Gustavo)\ **Replies:** 2\ **Last updated:** [25 March 2022 12:03 UTC](https://bempp.discourse.group/t/problems-using-ntd-operator/128 "2022-03-25T12:03:57Z")
Solved by pulling the latest docker image. Thanks Hi, I have the following line of code in my notebook: ntd = bempp.api.operators.boundary.helmholtz.osrc\_ntd(space, k) and it gives me the following error: Attribut… --- ## [Cylinders origin](https://bempp.discourse.group/t/cylinders-origin/122)
**Author:** [@bartek](https://bempp.discourse.group/u/bartek)\ **Replies:** 2\ **Last updated:** [9 March 2022 16:15 UTC](https://bempp.discourse.group/t/cylinders-origin/122 "2022-03-09T16:15:15Z")
Hello Everyone, BEM++ seems to be a great and powerfull tool, however I have some stupid problem with a cylinder shape, trying to find the solutions of the Masxwell’s exquation for a radio wave. The object: bempp.api.s… --- ## [Memory utilization for large problems](https://bempp.discourse.group/t/memory-utilization-for-large-problems/120)
**Author:** [@Fabian](https://bempp.discourse.group/u/Fabian)\ **Replies:** 1\ **Last updated:** [8 March 2022 09:49 UTC](https://bempp.discourse.group/t/memory-utilization-for-large-problems/120 "2022-03-08T09:49:56Z")
Hi everyone! I’m currently struggling with large acoustic problems. The number of nodes/elements yields to an overload of RAM. Is there any way to write matrix entries, e.g. from boundary operators, block-wise in temp… --- ## [How to calculate grid function value at arbitrary points](https://bempp.discourse.group/t/how-to-calculate-grid-function-value-at-arbitrary-points/117)
**Author:** [@piman](https://bempp.discourse.group/u/piman)\ **Replies:** 1\ **Last updated:** [8 March 2022 09:29 UTC](https://bempp.discourse.group/t/how-to-calculate-grid-function-value-at-arbitrary-points/117 "2022-03-08T09:29:47Z")
Hi all, I see bempp.api.GridFunction.evaluate\_on\_element\_centers() and bempp.api.GridFunction.evaluate\_on\_vertices() functions that evaluate the grid function value at the grid element centers and at the grid vertices. … --- ## [How to access matrix entries of boundary operators](https://bempp.discourse.group/t/how-to-access-matrix-entries-of-boundary-operators/115)
**Author:** [@Fabian](https://bempp.discourse.group/u/Fabian)\ **Replies:** 2\ **Last updated:** [25 January 2022 12:02 UTC](https://bempp.discourse.group/t/how-to-access-matrix-entries-of-boundary-operators/115 "2022-01-25T12:02:50Z")
Hi everyone. I’m still new to bempp, so I hope someone of you could answer my question. During solving acoustic problems with bempp using the Burton-Miller method, I came across some major differences from the obtained … --- ## [Sound emission from a mesh triangle or vertex](https://bempp.discourse.group/t/sound-emission-from-a-mesh-triangle-or-vertex/113)
**Author:** [@Gustavo](https://bempp.discourse.group/u/Gustavo)\ **Replies:** 0\ **Last updated:** [21 January 2022 10:17 UTC](https://bempp.discourse.group/t/sound-emission-from-a-mesh-triangle-or-vertex/113 "2022-01-21T10:17:41Z")
Hi, I am pretty new to BEMP, and probably this is a silly question, but is better to ask the experts than to be stuck on a loop of trial and error indefinitely… In this tutorial: Jupyter Notebook Viewer we have scatter… --- ## ['Field' in Bistatic RCS tutorial](https://bempp.discourse.group/t/field-in-bistatic-rcs-tutorial/111)
**Author:** [@DAWardle](https://bempp.discourse.group/u/DAWardle)\ **Replies:** 5\ **Last updated:** [20 January 2022 12:32 UTC](https://bempp.discourse.group/t/field-in-bistatic-rcs-tutorial/111 "2022-01-20T12:32:50Z")
Hi Bempp. Near the end of the Bistatic RCS tutorial there’s a line of code: exterior\_values = -epot0\_ext \* sol\[1\] - mpot0\_ext \* sol\[0\] I think exterior\_values is an array of electric field (E) values in the host medi… --- ## [The cause of Asymmetric Matrix in Bempp](https://bempp.discourse.group/t/the-cause-of-asymmetric-matrix-in-bempp/109)
**Author:** [@LCheng](https://bempp.discourse.group/u/LCheng)\ **Replies:** 5\ **Last updated:** [29 November 2021 13:09 UTC](https://bempp.discourse.group/t/the-cause-of-asymmetric-matrix-in-bempp/109 "2021-11-29T13:09:38Z")
I am studying the acoustic scattering simulation. I found that the assembled matrix is asymmetric for Bempp. But it is strange because the equation solved in \[BEM for Acoustic scattering \]((7) (PDF) Fast Methods applied … --- ## [Problems running BEMpp under Docker](https://bempp.discourse.group/t/problems-running-bempp-under-docker/107)
**Author:** [@DAWardle](https://bempp.discourse.group/u/DAWardle)\ **Replies:** 10\ **Last updated:** [29 November 2021 11:12 UTC](https://bempp.discourse.group/t/problems-running-bempp-under-docker/107 "2021-11-29T11:12:48Z")
Hi everyone. I pulled the Docker image of BEMpp yesterday on a computer at work using: docker pull bempp/cl-notebook:latest The pull seemed to complete OK without errors. I then was able to get a JupyterLab notebook … --- ## [H2Opus library integration into bempp](https://bempp.discourse.group/t/h2opus-library-integration-into-bempp/108)
**Author:** [@piman](https://bempp.discourse.group/u/piman)\ **Replies:** 0\ **Last updated:** [23 November 2021 09:09 UTC](https://bempp.discourse.group/t/h2opus-library-integration-into-bempp/108 "2021-11-23T09:09:45Z")
Hi, I have found H2Opus library, a performance-oriented library for hierarchical matrices. It can be run on GPU, multi GPU, computational cluster cluster etc. and looks very efficient. At the end of the article they wand… --- ## [Docker installation POCL error](https://bempp.discourse.group/t/docker-installation-pocl-error/103)
**Author:** [@AndrewG](https://bempp.discourse.group/u/AndrewG)\ **Replies:** 5\ **Last updated:** [22 November 2021 09:43 UTC](https://bempp.discourse.group/t/docker-installation-pocl-error/103 "2021-11-22T09:43:55Z")
Hi BEMPP team, I’m trying to use BEMPP-CL for the first time. I used the docker installation, and ran the laplace\_interior\_dirichlet.ipynb notebook. Error message is pasted below. Machine Linux Mint 20.2. If I understan… --- ## [The Minor Influence of Vector Length on the Final Results](https://bempp.discourse.group/t/the-minor-influence-of-vector-length-on-the-final-results/106)
**Author:** [@LCheng](https://bempp.discourse.group/u/LCheng)\ **Replies:** 2\ **Last updated:** [19 November 2021 11:53 UTC](https://bempp.discourse.group/t/the-minor-influence-of-vector-length-on-the-final-results/106 "2021-11-19T11:53:52Z")
Hi, Bempp team, I am testing the vectorization acceleration for Bempp using OpenCL on ARM v8 CPU. The vector length of ARM V8 is 4, but I found that the assembled matrix with the vectorization mismatches with the non-ve… --- ## [Sound-hard Burton miller acoustic scattering](https://bempp.discourse.group/t/sound-hard-burton-miller-acoustic-scattering/45)
**Author:** [@Rasmus](https://bempp.discourse.group/u/Rasmus)\ **Replies:** 6\ **Last updated:** [10 November 2021 12:18 UTC](https://bempp.discourse.group/t/sound-hard-burton-miller-acoustic-scattering/45 "2021-11-10T12:18:44Z")
Hello First of all, thanks for making this software. I’m a masters student currently working with BEMPP to solve acoustic scattering problems off of a human head model to numerically calculate HRTF’s. As I have unders… --- ## [Inhomogeneous interior Neumann problem](https://bempp.discourse.group/t/inhomogeneous-interior-neumann-problem/104)
**Author:** [@DuncanvdH](https://bempp.discourse.group/u/DuncanvdH)\ **Replies:** 0\ **Last updated:** [2 November 2021 13:26 UTC](https://bempp.discourse.group/t/inhomogeneous-interior-neumann-problem/104 "2021-11-02T13:26:09Z")
I try to solve an interior inhomogeneous Neumann problem for the so-called Stokes-Joukowsky potential. This (velocity) potential describes the flow inside a completely filled container under rotational excitation. I am … --- ## [Restrict grid to particular segment](https://bempp.discourse.group/t/restrict-grid-to-particular-segment/97)
**Author:** [@DuncanvdH](https://bempp.discourse.group/u/DuncanvdH)\ **Replies:** 1\ **Last updated:** [16 September 2021 21:07 UTC](https://bempp.discourse.group/t/restrict-grid-to-particular-segment/97 "2021-09-16T21:07:57Z")
If I create a grid function for a particular function space on a segment of the grid, still the complete grid is visualized, although the grid function is only shown on the segment it is defined on. Is there a way to on… --- ## [The definition mismatch of the double layer operator](https://bempp.discourse.group/t/the-definition-mismatch-of-the-double-layer-operator/96)
**Author:** [@LCheng](https://bempp.discourse.group/u/LCheng)\ **Replies:** 2\ **Last updated:** [16 September 2021 01:24 UTC](https://bempp.discourse.group/t/the-definition-mismatch-of-the-double-layer-operator/96 "2021-09-16T01:24:57Z")
Hello, I found that the definition of the double layer on the “Bempp book” Bempp book is not matched with the publication(E. V. Wout, P. Gelat, T. Betcke and S. Arridge, 138(5), JASA, 2015). I have checked the Bempp c… --- ## [Feature gpu for 0.2.4](https://bempp.discourse.group/t/feature-gpu-for-0-2-4/94)
**Author:** [@hellojxt](https://bempp.discourse.group/u/hellojxt)\ **Replies:** 3\ **Last updated:** [16 August 2021 19:34 UTC](https://bempp.discourse.group/t/feature-gpu-for-0-2-4/94 "2021-08-16T19:34:12Z")
The code of “Solving your first problem with Bempp” cannot run under bempp 0.2.4. The error it causes: RuntimeError: Could not find suitable OpenCL CPU driver. I read the code of bempp 0.2.4 and found that it does not… --- ## [Coefficients of composition of function and gridfunction](https://bempp.discourse.group/t/coefficients-of-composition-of-function-and-gridfunction/88)
**Author:** [@jnick](https://bempp.discourse.group/u/jnick)\ **Replies:** 2\ **Last updated:** [20 July 2021 13:04 UTC](https://bempp.discourse.group/t/coefficients-of-composition-of-function-and-gridfunction/88 "2021-07-20T13:04:29Z")
When implementing a solver for a nonlinear BIE formulation (by Newton’s method) I stumbled upon the following problem: Given a nonlinear function a:\\mathbb R^3\\rightarrow \\mathbb R^3 and coefficients c\\in \\mathbb R^{\\te… --- ## [Ways to approximate singular surface integral in BEMPP](https://bempp.discourse.group/t/ways-to-approximate-singular-surface-integral-in-bempp/91)
**Author:** [@Dr.Gardiner](https://bempp.discourse.group/u/Dr.Gardiner)\ **Replies:** 5\ **Last updated:** [14 July 2021 18:37 UTC](https://bempp.discourse.group/t/ways-to-approximate-singular-surface-integral-in-bempp/91 "2021-07-14T18:37:59Z")
Consider the following integral I(\\vec z) = \\int\_{\\partial\\Omega} \\frac{e^{0.1(x\_1+2x\_2+3x\_3)}}{|\\vec z-\\vec x|} \\,dL(x), \\hspace{3mm}\\\\ \\vec x = (x\_1,x\_2,x\_3) \\in \\Omega, \\hspace{3mm} \\vec z = (z\_1,z\_2,z\_3) \\in \\par… --- ## [The Cross-node Parallelism Issue](https://bempp.discourse.group/t/the-cross-node-parallelism-issue/86)
**Author:** [@LCheng](https://bempp.discourse.group/u/LCheng)\ **Replies:** 3\ **Last updated:** [21 June 2021 08:42 UTC](https://bempp.discourse.group/t/the-cross-node-parallelism-issue/86 "2021-06-21T08:42:26Z")
Hi, dear bempp team, I am very appreciated about this excellent code and the platform which we can communicate with each other about BEM. I am planning to verify the capability of Bempp in simulating large-scale acousti… --- ## [The thread allocation issue related to the large-scale Problems](https://bempp.discourse.group/t/the-thread-allocation-issue-related-to-the-large-scale-problems/83)
**Author:** [@LCheng](https://bempp.discourse.group/u/LCheng)\ **Replies:** 2\ **Last updated:** [21 June 2021 03:34 UTC](https://bempp.discourse.group/t/the-thread-allocation-issue-related-to-the-large-scale-problems/83 "2021-06-21T03:34:10Z")
Hi, thanks for the very nice open source code. I am dealing with large-scale acoustic problems using Bempp-cl. Yesterday, when I tried the first benmark case with element number equal to 300 thousands, I am puzzled about… --- ## [Direction of RWG basis function in bempp](https://bempp.discourse.group/t/direction-of-rwg-basis-function-in-bempp/85)
**Author:** [@piman](https://bempp.discourse.group/u/piman)\ **Replies:** 1\ **Last updated:** [15 June 2021 08:30 UTC](https://bempp.discourse.group/t/direction-of-rwg-basis-function-in-bempp/85 "2021-06-15T08:30:59Z")
Hi all, To correlate RWG elements in bempp and in my own code, I’m interested in the order and direction of RWG basis function in bempp. As I can see, order of RWG elements is similar to the order of edges in grid.edges… --- ## [Interface to kernel-independent FMM-like assembler](https://bempp.discourse.group/t/interface-to-kernel-independent-fmm-like-assembler/67)
**Author:** [@piman](https://bempp.discourse.group/u/piman)\ **Replies:** 3\ **Last updated:** [28 May 2021 11:28 UTC](https://bempp.discourse.group/t/interface-to-kernel-independent-fmm-like-assembler/67 "2021-05-28T11:28:55Z")
Dear bempp-cl team, I’m thinking of using a kernel-independent FFM-like assembler to speed up EM simulation, such as \[h2tools\] (Bitbucket). To apply it, I need a function that calculates a submatrix of matrix A based on… --- ## [Well-conditioned formulation for open surfaces (Maxwell)](https://bempp.discourse.group/t/well-conditioned-formulation-for-open-surfaces-maxwell/75)
**Author:** [@piman](https://bempp.discourse.group/u/piman)\ **Replies:** 2\ **Last updated:** [28 May 2021 09:39 UTC](https://bempp.discourse.group/t/well-conditioned-formulation-for-open-surfaces-maxwell/75 "2021-05-28T09:39:11Z")
Hi all, I seek a well-conditioned formulation for electromagnetic scattering on a perfectly conductive screens. In \[1\] it is proposed several well-conditioned formulations, but as I can see they work only for closed sur… --- ## [Convective Wave Equation](https://bempp.discourse.group/t/convective-wave-equation/81)
**Author:** [@LCheng](https://bempp.discourse.group/u/LCheng)\ **Replies:** 2\ **Last updated:** [24 May 2021 02:44 UTC](https://bempp.discourse.group/t/convective-wave-equation/81 "2021-05-24T02:44:30Z")
Hi, do you think it is easy to extend the present bempp to consider the convective flow effect? It means that the convective wave equation in the frequency domain needs to be solved. It will be much more meaningful for a… --- ## [Problems running BEMPP on Mac](https://bempp.discourse.group/t/problems-running-bempp-on-mac/66)
**Author:** [@SebastianK](https://bempp.discourse.group/u/SebastianK)\ **Replies:** 3\ **Last updated:** [23 May 2021 18:31 UTC](https://bempp.discourse.group/t/problems-running-bempp-on-mac/66 "2021-05-23T18:31:10Z")
I am following the installation steps to install bempp 0.2.2 from source on my mac (Catalina 10.15.7). After installation I am getting the following error running sphere scattering example: from bempp.api.linalg import… --- ## [Robin boundary condition for free surface flow](https://bempp.discourse.group/t/robin-boundary-condition-for-free-surface-flow/78)
**Author:** [@DuncanvdH](https://bempp.discourse.group/u/DuncanvdH)\ **Replies:** 1\ **Last updated:** [30 April 2021 23:05 UTC](https://bempp.discourse.group/t/robin-boundary-condition-for-free-surface-flow/78 "2021-04-30T23:05:53Z")
I am interested in solving a generalized eigenvalue problem to find the natural sloshing frequencies of an arbitrarily shaped basin. The physics is described with a non-linear boundary condition that can be linearised to… [Previous page](https://bempp.discourse.group/latest.md?page=2) [Next page](https://bempp.discourse.group/latest.md?page=4)