# General Discussion **URL:** https://community.freefem.org/c/general-discussion/7.md?page=52 [Latest](https://community.freefem.org/latest.md) · [Categories](https://community.freefem.org/categories.md) **Page:** 53 --- ## [Méthodes des éléments frontières](https://community.freefem.org/t/methodes-des-elements-frontieres/1412)
**Author:** [@Jamal](https://community.freefem.org/u/Jamal)\ **Replies:** 1\ **Last updated:** [January 6, 2022, 8:46am UTC](https://community.freefem.org/t/methodes-des-elements-frontieres/1412 "2022-01-06T08:46:21Z")
Hello everyone I am looking for an example to solve a PDE with the boundary element method in freefem++ --- ## [Import/interpolate data from MatLAB to FreeFEM++](https://community.freefem.org/t/import-interpolate-data-from-matlab-to-freefem/1405)
**Author:** [@Robert](https://community.freefem.org/u/Robert)\ **Replies:** 0\ **Last updated:** [December 31, 2021, 3:10pm UTC](https://community.freefem.org/t/import-interpolate-data-from-matlab-to-freefem/1405 "2021-12-31T15:10:04Z")
Dear forum, First of all, I wish a Happy New Year to everyone. Secondly, thank you for sharing the discussions from FreeFEM++ days for those who couldn’t attend live. I want to perform a stability analysis on a 2D geom… --- ## [Options to impose Dirichlet BC with "ON"](https://community.freefem.org/t/options-to-impose-dirichlet-bc-with-on/1399)
**Author:** [@Loic](https://community.freefem.org/u/Loic)\ **Replies:** 4\ **Last updated:** [December 26, 2021, 2:25pm UTC](https://community.freefem.org/t/options-to-impose-dirichlet-bc-with-on/1399 "2021-12-26T14:25:56Z")
Hello all, @prj, @frederichecht, where I could find all the options to impose dirichlet boundary conditions with “on” like this: on(1, u=g, tgv=xx) with xx=-1; -2; -10 ; … Thank you for your help, Best regards, Loïc, … --- ## [Bilinear symmetrical term as the product of two means](https://community.freefem.org/t/bilinear-symmetrical-term-as-the-product-of-two-means/1403)
**Author:** [@munch](https://community.freefem.org/u/munch)\ **Replies:** 1\ **Last updated:** [December 24, 2021, 12:47pm UTC](https://community.freefem.org/t/bilinear-symmetrical-term-as-the-product-of-two-means/1403 "2021-12-24T12:47:37Z")
Hi all, is there a way to consider bilinear term of the form (\\int\_\\Omega \\phi dx ) (\\int\_\\Omega \\phi\_t dx) \\phi\_t being the test function ? Thanks, arnaud --- ## [Fatal error with PMPI\_WaitAny](https://community.freefem.org/t/fatal-error-with-pmpi-waitany/1395)
**Author:** [@zcwang6](https://community.freefem.org/u/zcwang6)\ **Replies:** 18\ **Last updated:** [December 23, 2021, 5:31pm UTC](https://community.freefem.org/t/fatal-error-with-pmpi-waitany/1395 "2021-12-23T17:31:55Z")
Dear Prj, currently I saw a strange error with my FF code, when I run it on my school cluster; " Fatal error in PMPI\_Waitall: Other MPI error, error stack: " It happened randomly kind of. I believe this problem only h… --- ## [How to define a test function for H^(1/2)](https://community.freefem.org/t/how-to-define-a-test-function-for-h-1-2/1401)
**Author:** [@sumantkr](https://community.freefem.org/u/sumantkr)\ **Replies:** 2\ **Last updated:** [December 23, 2021, 2:10pm UTC](https://community.freefem.org/t/how-to-define-a-test-function-for-h-1-2/1401 "2021-12-23T14:10:17Z")
Dear all, @prj @frederichecht How to define a test space (trace space) H^(1/2) over an interface of two sub-domains? or, the only restriction of a test space that is defined for a sub-domain over the interface will wo… --- ## [How to control on a specific part of domain](https://community.freefem.org/t/how-to-control-on-a-specific-part-of-domain/1372)
**Author:** [@sumantkr](https://community.freefem.org/u/sumantkr)\ **Replies:** 5\ **Last updated:** [December 19, 2021, 1:03pm UTC](https://community.freefem.org/t/how-to-control-on-a-specific-part-of-domain/1372 "2021-12-19T13:03:07Z")
Dear All How can we update a solution on a part of a domain? For example: in an edge (right vertical) of a unit square, how could we take control. --- ## [Tegten assertion fail](https://community.freefem.org/t/tegten-assertion-fail/1398)
**Author:** [@xiaojiemo](https://community.freefem.org/u/xiaojiemo)\ **Replies:** 0\ **Last updated:** [December 19, 2021, 7:35am UTC](https://community.freefem.org/t/tegten-assertion-fail/1398 "2021-12-19T07:35:36Z")
hello,everyone. I am building a sphere using mmg and tegten,the error information is like below, the code is, is there anyone can tell me which parameter to correct works? --- ## [Func with fespace argument](https://community.freefem.org/t/func-with-fespace-argument/1394)
**Author:** [@terribab](https://community.freefem.org/u/terribab)\ **Replies:** 0\ **Last updated:** [December 16, 2021, 2:21pm UTC](https://community.freefem.org/t/func-with-fespace-argument/1394 "2021-12-16T14:21:28Z")
Is it possible to define a function that takes as input a fespace type of variable? take as example this synthetic code: varf a(u,v) = int2d(Th\[i\]) (dx(u)\*dx(v) + dy(u)\*dy(v)); func matrix aa(fespace Xh1, fespace Xh2)… --- ## [Build a local mesh](https://community.freefem.org/t/build-a-local-mesh/1382)
**Author:** [@larismartins](https://community.freefem.org/u/larismartins)\ **Replies:** 7\ **Last updated:** [December 14, 2021, 9:38pm UTC](https://community.freefem.org/t/build-a-local-mesh/1382 "2021-12-14T21:38:29Z")
Hi, is it possible to build local mesh in 2D? If I’m using: mesh Th = square(2,2); as a global mesh, and I want to build a refined local mesh for each triangle. Can I do that? How? --- ## [Help with mesh compatibility](https://community.freefem.org/t/help-with-mesh-compatibility/1392)
**Author:** [@larismartins](https://community.freefem.org/u/larismartins)\ **Replies:** 0\ **Last updated:** [December 14, 2021, 5:07pm UTC](https://community.freefem.org/t/help-with-mesh-compatibility/1392 "2021-12-14T17:07:20Z")
Sorry for doing a lot of questions. But I did the following: // paraview plot load "iovtk" int NbTriangles = 8; //------------------Building mesh-------------------- int localRef = 4; //-----------------Global mesh---… --- ## [Read 2D mesh from triangle](https://community.freefem.org/t/read-2d-mesh-from-triangle/1390)
**Author:** [@larismartins](https://community.freefem.org/u/larismartins)\ **Replies:** 1\ **Last updated:** [December 14, 2021, 4:37pm UTC](https://community.freefem.org/t/read-2d-mesh-from-triangle/1390 "2021-12-14T16:37:43Z")
Hi, I have a mesh file generate by triangle, so I have files of the type: .ele .node .neigh .edge .poly Is it possible to read this mesh in freefem? How? --- ## [Error operator when returning a mesh vector](https://community.freefem.org/t/error-operator-when-returning-a-mesh-vector/1389)
**Author:** [@RaMattoso](https://community.freefem.org/u/RaMattoso)\ **Replies:** 2\ **Last updated:** [December 14, 2021, 4:36pm UTC](https://community.freefem.org/t/error-operator-when-returning-a-mesh-vector/1389 "2021-12-14T16:36:10Z")
Hello fellows! I’m optimizing one of my codes in freefem by creating functions. But i’m having some issue when I try to transfer a mesh vector from idp file to edp file. The codes follow "meshcreation.idp" func mesh… --- ## [Segmentation Error](https://community.freefem.org/t/segmentation-error/1386)
**Author:** [@sevinurafni](https://community.freefem.org/u/sevinurafni)\ **Replies:** 2\ **Last updated:** [December 14, 2021, 4:00pm UTC](https://community.freefem.org/t/segmentation-error/1386 "2021-12-14T16:00:44Z")
Hello, I came across a segmentation fault when trying to run membrane program in the documentation. I have compiled Freefem++ 4.6 on Xubuntu 20.04. Any ideas on how to solve this? Thank you. real theta = 4.\*pi/3.; re… --- ## [Vector of meshes](https://community.freefem.org/t/vector-of-meshes/1385)
**Author:** [@larismartins](https://community.freefem.org/u/larismartins)\ **Replies:** 1\ **Last updated:** [December 13, 2021, 6:05pm UTC](https://community.freefem.org/t/vector-of-meshes/1385 "2021-12-13T18:05:11Z")
Is it possible to create a vector of meshes? --- ## [PETSc issue while running on FF++ -cs 15.2](https://community.freefem.org/t/petsc-issue-while-running-on-ff-cs-15-2/1380)
**Author:** [@zhk](https://community.freefem.org/u/zhk)\ **Replies:** 7\ **Last updated:** [December 13, 2021, 8:46am UTC](https://community.freefem.org/t/petsc-issue-while-running-on-ff-cs-15-2/1380 "2021-12-13T08:46:11Z")
While using FREEFEM++ -cs 15.2, I am facing this problem Error line number 754, in file macro: buildOverlapEdgePeriodicRecursive in C:\\Program Files (x86)\\FreeFem++\\idp\\macro\_ddm.idp, before token mpiWtime current line… --- ## [Two nearly self-intersecting facets](https://community.freefem.org/t/two-nearly-self-intersecting-facets/1384)
**Author:** [@xiaojiemo](https://community.freefem.org/u/xiaojiemo)\ **Replies:** 0\ **Last updated:** [December 13, 2021, 1:06am UTC](https://community.freefem.org/t/two-nearly-self-intersecting-facets/1384 "2021-12-13T01:06:45Z")
hello,everyone. I am building a network which consists of a cylinder and an array of solid particle in it. I tried to build 3D curve and used tegten to build the mesh. The procedure said that my whole code is like be… --- ## [DMplex can not read region number](https://community.freefem.org/t/dmplex-can-not-read-region-number/1368)
**Author:** [@zcwang6](https://community.freefem.org/u/zcwang6)\ **Replies:** 4\ **Last updated:** [December 10, 2021, 12:03pm UTC](https://community.freefem.org/t/dmplex-can-not-read-region-number/1368 "2021-12-10T12:03:03Z")
Hello, I am trying to read a binary mesh from GMSH by DMplex; However, it seems DMplex can not read the correct region number; I also tried gmshload3 which works well. I am attaching my code and input mesh here for you… --- ## [Compute values at certain points](https://community.freefem.org/t/compute-values-at-certain-points/1378)
**Author:** [@s.h.tong](https://community.freefem.org/u/s.h.tong)\ **Replies:** 1\ **Last updated:** [December 10, 2021, 5:34am UTC](https://community.freefem.org/t/compute-values-at-certain-points/1378 "2021-12-10T05:34:22Z")
I want to compute the value of u at several certain points. Where can I add the positions? Thanks --- ## [Applying concentrated force](https://community.freefem.org/t/applying-concentrated-force/1377)
**Author:** [@distractor](https://community.freefem.org/u/distractor)\ **Replies:** 0\ **Last updated:** [December 9, 2021, 6:41pm UTC](https://community.freefem.org/t/applying-concentrated-force/1377 "2021-12-09T18:41:31Z")
How do I apply concentrated force in FF++? So assume I have force Vh(Th, P1); Vh fx, fy, fz; where force = (fx, fy, fz). Now In problem definition, I want to apply these forces to the nodes, for example in linear elas… --- ## [10 node tetrahedral element](https://community.freefem.org/t/10-node-tetrahedral-element/1371)
**Author:** [@distractor](https://community.freefem.org/u/distractor)\ **Replies:** 1\ **Last updated:** [December 7, 2021, 4:43pm UTC](https://community.freefem.org/t/10-node-tetrahedral-element/1371 "2021-12-07T16:43:14Z")
Does FreeFem++ support the 10 node tetrahedral elements or only the simple 4 node tetrahedrons If yes, what are they? The P2b or something else? --- ## ["Err" parameter in adaptmesh](https://community.freefem.org/t/err-parameter-in-adaptmesh/1370)
**Author:** [@ruffi92](https://community.freefem.org/u/ruffi92)\ **Replies:** 0\ **Last updated:** [December 7, 2021, 9:46am UTC](https://community.freefem.org/t/err-parameter-in-adaptmesh/1370 "2021-12-07T09:46:47Z")
I try to make a comparison between the adaption with the command “adaptmesh” (that use the hessian method) and one that use the recovery-gradient method with zienchiewiz-zhu estimator (developed by myself). But i don’t … --- ## [Interpolation with zero extension](https://community.freefem.org/t/interpolation-with-zero-extension/1106)
**Author:** [@yongxing](https://community.freefem.org/u/yongxing)\ **Replies:** 1\ **Last updated:** [December 6, 2021, 12:55pm UTC](https://community.freefem.org/t/interpolation-with-zero-extension/1106 "2021-12-06T12:55:35Z")
interpolate from a small mesh Ths to a larger mesh Th, for example fespace Vh(Th, P2); Vh u; fespace Vhs(Ths, P2); Vh us=sin(x+y); In default, u=us would extend the value of us to the whole Th, how can we let u=0 on… --- ## [The problem definition in G. Sadaka's Wave Equation example](https://community.freefem.org/t/the-problem-definition-in-g-sadakas-wave-equation-example/1366)
**Author:** [@kilasuelika](https://community.freefem.org/u/kilasuelika)\ **Replies:** 1\ **Last updated:** [December 5, 2021, 11:40am UTC](https://community.freefem.org/t/the-problem-definition-in-g-sadakas-wave-equation-example/1366 "2021-12-05T11:40:59Z")
G. Sadaka provide an examplein solving Wave Equation. Math equation is: The problem definition in Sadaka’s code is: problem tambour(uh,vh) = int2d(Th)(uh\*vh + Grad(uh)'\*Grad(vh)\*(c\*dt)^2\*.5 ) + int2d(Th)(Grad(… --- ## [Moving mesh without movemesh()](https://community.freefem.org/t/moving-mesh-without-movemesh/1090)
**Author:** [@yongxing](https://community.freefem.org/u/yongxing)\ **Replies:** 3\ **Last updated:** [December 4, 2021, 3:37pm UTC](https://community.freefem.org/t/moving-mesh-without-movemesh/1090 "2021-12-04T15:37:37Z")
Can we directly move the coordinates of a mesh’s vertices without using the function of movemesh()? both P1 and P2 elements? --- ## [Error convergence bug](https://community.freefem.org/t/error-convergence-bug/1360)
**Author:** [@Qianrui](https://community.freefem.org/u/Qianrui)\ **Replies:** 3\ **Last updated:** [December 4, 2021, 3:36pm UTC](https://community.freefem.org/t/error-convergence-bug/1360 "2021-12-04T15:36:30Z")
Hi,To solve an equation, the order of error convergence is 2 in theory, but the result of numerical simulation is 1 in theory. Why ? --- ## [Creating an array of spheres](https://community.freefem.org/t/creating-an-array-of-spheres/1361)
**Author:** [@xiaojiemo](https://community.freefem.org/u/xiaojiemo)\ **Replies:** 3\ **Last updated:** [December 4, 2021, 3:33pm UTC](https://community.freefem.org/t/creating-an-array-of-spheres/1361 "2021-12-04T15:33:39Z")
hello.everyone.I am struggling of creating an array of sphere and I have tried through “mmgs”. while it completely cannnot work. Is there anyone can provide suggestions? --- ## [Does FreeFEM support solve ODE?](https://community.freefem.org/t/does-freefem-support-solve-ode/1365)
**Author:** [@kilasuelika](https://community.freefem.org/u/kilasuelika)\ **Replies:** 1\ **Last updated:** [December 4, 2021, 3:31pm UTC](https://community.freefem.org/t/does-freefem-support-solve-ode/1365 "2021-12-04T15:31:29Z")
I want to know that it if I can use FreeFEM to solve a simple ODE. Such as: dx/dt=\[sin(x1)+x2,cos(x2)\] I have searched on the Internet but didn’t find any topics about ODE solving in FreeFEM. --- ## [Spatial Co-ordinate of Maximum Value of Variable](https://community.freefem.org/t/spatial-co-ordinate-of-maximum-value-of-variable/1364)
**Author:** [@D\_N\_Sarkar](https://community.freefem.org/u/D_N_Sarkar)\ **Replies:** 1\ **Last updated:** [December 4, 2021, 2:57pm UTC](https://community.freefem.org/t/spatial-co-ordinate-of-maximum-value-of-variable/1364 "2021-12-04T14:57:53Z")
Say I have the following code: int nn = 50; mesh Th = square(nn, nn); fespace Vh(Th, P1); Vh u; u = sin(x); I can get the maximum value of ‘u’ by: real maxValueU = u\[\].max; How do I get the values of x and y coor… --- ## [Vizualization on adjacent meshes with freefem](https://community.freefem.org/t/vizualization-on-adjacent-meshes-with-freefem/1363)
**Author:** [@Loic](https://community.freefem.org/u/Loic)\ **Replies:** 0\ **Last updated:** [December 2, 2021, 12:49pm UTC](https://community.freefem.org/t/vizualization-on-adjacent-meshes-with-freefem/1363 "2021-12-02T12:49:04Z")
Hello all, I have different velocity fields vk\[ \] define on adjacent (non-overlapping) meshes ThK and on FE space VhK (each mesh shares one adjacent boundary edge with its neighbour) How can I gather all these velocit… [Previous page](https://community.freefem.org/c/general-discussion/7.md?page=51) [Next page](https://community.freefem.org/c/general-discussion/7.md?page=53)