# Feature Request **URL:** https://community.freefem.org/c/features-request/6.md [Latest](https://community.freefem.org/latest.md) · [Categories](https://community.freefem.org/categories.md) --- ## [About the Feature Request category](https://community.freefem.org/t/about-the-feature-request-category/14)
**Author:** [@franck.lahaye](https://community.freefem.org/u/franck.lahaye)\ **Replies:** 1\ **Last updated:** [December 30, 2025, 4:26am UTC](https://community.freefem.org/t/about-the-feature-request-category/14 "2025-12-30T04:26:06Z")
Tell us which features we should implement next --- ## [Can you someone please help to write last term of the first and third equation in the variational form](https://community.freefem.org/t/can-you-someone-please-help-to-write-last-term-of-the-first-and-third-equation-in-the-variational-form/3298)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 4\ **Last updated:** [April 13, 2026, 4:06pm UTC](https://community.freefem.org/t/can-you-someone-please-help-to-write-last-term-of-the-first-and-third-equation-in-the-variational-form/3298 "2026-04-13T16:06:28Z")
Here , is the variational form: I have tried to write last term of the first equation and third equation in 2D but i am getting product of two unknows present there which is not solvable by FreeFem++. My trial: (cv… --- ## [Hybridizable discontinuius Galerkin method for laplace equation](https://community.freefem.org/t/hybridizable-discontinuius-galerkin-method-for-laplace-equation/4169)
**Author:** [@debendra](https://community.freefem.org/u/debendra)\ **Replies:** 1\ **Last updated:** [December 30, 2025, 4:49am UTC](https://community.freefem.org/t/hybridizable-discontinuius-galerkin-method-for-laplace-equation/4169 "2025-12-30T04:49:00Z")
Can you provide a reference for hybridizable discontinuous Galerkin code for laplace equation? -/Delta u=f, u=0 on boundary, domain /Omega=Unitsquare. --- ## [Is the KMV Element Available in FreeFEM?](https://community.freefem.org/t/is-the-kmv-element-available-in-freefem/4142)
**Author:** [@thingway](https://community.freefem.org/u/thingway)\ **Replies:** 4\ **Last updated:** [November 26, 2025, 12:58pm UTC](https://community.freefem.org/t/is-the-kmv-element-available-in-freefem/4142 "2025-11-26T12:58:00Z")
After reading the FreeFEM documentation, I could not find any function or element corresponding to the KMV (Kong-Mulder-Veldhuizen) element, as described on DefElement: https://defelement.org/elements/kong-mulder-veldhui… --- ## [Adding FreeFEM to nixpkgs](https://community.freefem.org/t/adding-freefem-to-nixpkgs/4101)
**Author:** [@simon](https://community.freefem.org/u/simon)\ **Replies:** 0\ **Last updated:** [October 15, 2025, 4:07pm UTC](https://community.freefem.org/t/adding-freefem-to-nixpkgs/4101 "2025-10-15T16:07:58Z")
I am a new NixOS User and it would be nice to have a nix package for FreeFEM. I would do this myself. But I am not that knowledgeable yet. --- ## [Positive part of an array, maximum of two arrays](https://community.freefem.org/t/positive-part-of-an-array-maximum-of-two-arrays/3954)
**Author:** [@fb77](https://community.freefem.org/u/fb77)\ **Replies:** 4\ **Last updated:** [June 11, 2025, 9:59am UTC](https://community.freefem.org/t/positive-part-of-an-array-maximum-of-two-arrays/3954 "2025-06-11T09:59:10Z")
Hi to the developers, It would be convenient to have built-in the max or min of an array and a real number, which means taking the max or min in each entry real\[int\] aa(nn),res(nn); real rr; res=max(aa,rr); would give… --- ## [Access SNESMonitorSet in PETSc plugin](https://community.freefem.org/t/access-snesmonitorset-in-petsc-plugin/3925)
**Author:** [@cmd](https://community.freefem.org/u/cmd)\ **Replies:** 6\ **Last updated:** [May 21, 2025, 4:50pm UTC](https://community.freefem.org/t/access-snesmonitorset-in-petsc-plugin/3925 "2025-05-21T16:50:39Z")
When using TSSolve(), we can define custom monitors using TSMonitorSet() as in: examples/hpddm/heat-TS-2d-PETSc.edp. Relevant source code here. Is there already an implemented approach to do something similar with SNES… --- ## [Need a Sample Code](https://community.freefem.org/t/need-a-sample-code/3695)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 1\ **Last updated:** [April 19, 2025, 8:56pm UTC](https://community.freefem.org/t/need-a-sample-code/3695 "2025-04-19T20:56:54Z")
Hello, all experts, Is there any demo code to write integral term of the following type of equation in FF++??. For integral term i have to used the following quadrature formula: I am facing problem to write the i… --- ## [Can PML be achieved?](https://community.freefem.org/t/can-pml-be-achieved/3763)
**Author:** [@syong](https://community.freefem.org/u/syong)\ **Replies:** 5\ **Last updated:** [February 25, 2025, 10:32am UTC](https://community.freefem.org/t/can-pml-be-achieved/3763 "2025-02-25T10:32:49Z")
In time-domain wave problems, PML (Perfect Match Layer) serves as an excellent artificial boundary, capable of addressing the pseudo-reflection phenomenon caused by truncation boundaries. Is it possible to implement this… --- ## [Implement structural elements](https://community.freefem.org/t/implement-structural-elements/3741)
**Author:** [@syong](https://community.freefem.org/u/syong)\ **Replies:** 0\ **Last updated:** [February 11, 2025, 11:06am UTC](https://community.freefem.org/t/implement-structural-elements/3741 "2025-02-11T11:06:37Z")
Sometimes, structural elements, such as beam elements and truss elements and so on, are needed in calculations. They are mainly used in civil engineering. It would be best if relevant options could be directly provided w… --- ## [Implement 1D integral in 3D simulation](https://community.freefem.org/t/implement-1d-integral-in-3d-simulation/3740)
**Author:** [@usiu5555](https://community.freefem.org/u/usiu5555)\ **Replies:** 0\ **Last updated:** [February 10, 2025, 6:59am UTC](https://community.freefem.org/t/implement-1d-integral-in-3d-simulation/3740 "2025-02-10T06:59:39Z")
Sometimes in simulations, we would want to reduce the dimensionality of a domain. For example in grain boundary diffusion (see https://www.doi.org/10.1088/1361-651x/ab1624), when considering the effect of diffusion on th… --- ## [Automatic Differentiation (AD)](https://community.freefem.org/t/automatic-differentiation-ad/2767)
**Author:** [@cmd](https://community.freefem.org/u/cmd)\ **Replies:** 1\ **Last updated:** [December 18, 2024, 1:52pm UTC](https://community.freefem.org/t/automatic-differentiation-ad/2767 "2024-12-18T13:52:19Z")
It has been some years since I’ve seen any updates on the development of an AD framework in FreeFEM. Obviously, this powerful feature is a huge undertaking, but I am curious whether any developers are currently working o… --- ## [Request for additional documentation on Petsc-related functions](https://community.freefem.org/t/request-for-additional-documentation-on-petsc-related-functions/3608)
**Author:** [@QZH\_xia](https://community.freefem.org/u/QZH_xia)\ **Replies:** 5\ **Last updated:** [December 18, 2024, 7:07am UTC](https://community.freefem.org/t/request-for-additional-documentation-on-petsc-related-functions/3608 "2024-12-18T07:07:08Z")
Hello, I initially learned Petsc and am now trying to use FreeFem to call Petsc. However, when I attempted to use it to solve problems, I found that FreeFem offers very little documentation regarding Petsc-related funct… --- ## [What will be replacement of lenEdge of 2D in 3D?](https://community.freefem.org/t/what-will-be-replacement-of-lenedge-of-2d-in-3d/3595)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 0\ **Last updated:** [November 22, 2024, 4:09pm UTC](https://community.freefem.org/t/what-will-be-replacement-of-lenedge-of-2d-in-3d/3595 "2024-11-22T16:09:01Z")
Hi, i want to know what is replacement of lenEdge in 3D?? What is the needed space for that?. Also, +intallfaces(Th)(jump(u)jump(v)(nTonEdge-1)), here what i write instead of nTonEdge in 3D DG. --- ## [I need two write the second term of the bilinear form in FreeFem++](https://community.freefem.org/t/i-need-two-write-the-second-term-of-the-bilinear-form-in-freefem/3581)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 2\ **Last updated:** [November 21, 2024, 10:27am UTC](https://community.freefem.org/t/i-need-two-write-the-second-term-of-the-bilinear-form-in-freefem/3581 "2024-11-21T10:27:56Z")
Can someone help me how to write the second term of the bilinear form?? Also, given that theta= 0 on boundary of the domain. --- ## [Mixing of composite and non-composite fe spaces](https://community.freefem.org/t/mixing-of-composite-and-non-composite-fe-spaces/3510)
**Author:** [@mhg](https://community.freefem.org/u/mhg)\ **Replies:** 1\ **Last updated:** [September 23, 2024, 12:22pm UTC](https://community.freefem.org/t/mixing-of-composite-and-non-composite-fe-spaces/3510 "2024-09-23T12:22:21Z")
It seems that currently the mixing of composite and non-composite fe spaces in a varf is not possible. For me it would be nice to do things like in the following simplified example: int nn = 30; mesh Th=square(nn,nn); m… --- ## [Error in Figure 58?](https://community.freefem.org/t/error-in-figure-58/3458)
**Author:** [@byanoff](https://community.freefem.org/u/byanoff)\ **Replies:** 1\ **Last updated:** [August 28, 2024, 2:40pm UTC](https://community.freefem.org/t/error-in-figure-58/3458 "2024-08-28T14:40:02Z")
This seemed like the most logical place to mention this: It seems like the arrows in Fig. 58 in the online documentation for the buildmesh command are pointing in the wrong direction. The surface is supposed to be on the… --- ## [Help please,need FreeFem++ code](https://community.freefem.org/t/help-please-need-freefem-code/3418)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 0\ **Last updated:** [July 29, 2024, 1:15pm UTC](https://community.freefem.org/t/help-please-need-freefem-code/3418 "2024-07-29T13:15:39Z")
r is a random number uniformly distributed on \[-0.005; 0.005\]. what i write the code of r in FreeFem++. Suppose u=r Then, what will be w=u^3-u-((\\nabla^2 )u); =u^3-u-\\Delta u Please help. I need FreeFem++ code of u… --- ## [intNd & on operators with array of int](https://community.freefem.org/t/intnd-on-operators-with-array-of-int/3410)
**Author:** [@PierreAntonetti](https://community.freefem.org/u/PierreAntonetti)\ **Replies:** 0\ **Last updated:** [July 23, 2024, 10:04pm UTC](https://community.freefem.org/t/intnd-on-operators-with-array-of-int/3410 "2024-07-23T22:04:30Z")
Hello, Do you think possible to extend the “intNd” and the “on” operators working with an array of labels int\[int\] ? Thanks --- ## [Option "rhsvarf" for on()](https://community.freefem.org/t/option-rhsvarf-for-on/3404)
**Author:** [@fb77](https://community.freefem.org/u/fb77)\ **Replies:** 8\ **Last updated:** [July 19, 2024, 1:00pm UTC](https://community.freefem.org/t/option-rhsvarf-for-on/3404 "2024-07-19T13:00:43Z")
This proposal is related to the discussion Behavior of varf with rhs and on() I think it would be useful to have a new option “rhsvarf” (=true or false) for the on() tool that sets Dirichlet BC. – If on() is used in t… --- ## [Getting problem to compute order of convergence in Poisson eqn when exact solution in unknown](https://community.freefem.org/t/getting-problem-to-compute-order-of-convergence-in-poisson-eqn-when-exact-solution-in-unknown/3306)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 6\ **Last updated:** [June 12, 2024, 3:06pm UTC](https://community.freefem.org/t/getting-problem-to-compute-order-of-convergence-in-poisson-eqn-when-exact-solution-in-unknown/3306 "2024-06-12T15:06:06Z")
Here, i am sharing my codes. Please help if anyone know. Moreover, I want to do simulation on this codes. How to do simulation on this code so that i can see my solution how simulate at different time??. poisson.edp (1.… --- ## [FreeFem++ code second order normal](https://community.freefem.org/t/freefem-code-second-order-normal/3140)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 5\ **Last updated:** [June 12, 2024, 8:16am UTC](https://community.freefem.org/t/freefem-code-second-order-normal/3140 "2024-06-12T08:16:10Z")
Can you please tell me what is the code of (del^u)/(del n^2), where n is the outward normal. That is i want to know freefem++ code of second order normal that is u\_nn . --- ## [How to solve Couples system of equations in FreeFem++](https://community.freefem.org/t/how-to-solve-couples-system-of-equations-in-freefem/3258)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 1\ **Last updated:** [June 11, 2024, 10:43am UTC](https://community.freefem.org/t/how-to-solve-couples-system-of-equations-in-freefem/3258 "2024-06-11T10:43:12Z")
Can you please help regarding how to solve couples system of equation in Freefem++ like Cahn-Hilliard equation involving non-linear terms. I have tried but showing error. --- ## [Can please help regarding L^{infinity} error and order computing](https://community.freefem.org/t/can-please-help-regarding-l-infinity-error-and-order-computing/3155)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 0\ **Last updated:** [April 28, 2024, 12:59pm UTC](https://community.freefem.org/t/can-please-help-regarding-l-infinity-error-and-order-computing/3155 "2024-04-28T12:59:09Z")
I need codes of computing L^{infinity} error and its order in FreeFem++ . Can you help me regarding this. I need codes for it. It will be very grateful i get a time dependent problem as example and finding this. --- ## [TAO Nonlinear Least-Squares integration](https://community.freefem.org/t/tao-nonlinear-least-squares-integration/3150)
**Author:** [@CarolinePascal](https://community.freefem.org/u/CarolinePascal)\ **Replies:** 1\ **Last updated:** [April 26, 2024, 11:17am UTC](https://community.freefem.org/t/tao-nonlinear-least-squares-integration/3150 "2024-04-26T11:17:56Z")
Hi everyone ! I’ve recently started using TAO to solve ill-posed problems, and I’d like to give a try to Tikhonov regularization methods. However, TAO least-squares solvers (TAO: Optimization Solvers — PETSc 3.21.0 docu… --- ## [Morley element 3D](https://community.freefem.org/t/morley-element-3d/3109)
**Author:** [@bcaval](https://community.freefem.org/u/bcaval)\ **Replies:** 0\ **Last updated:** [April 18, 2024, 8:47pm UTC](https://community.freefem.org/t/morley-element-3d/3109 "2024-04-18T20:47:15Z")
Hi, The subject is in the title. Does somebody knows how to extend the 2D Morley element to a 3D element? It would be useful for Second gradient theories. Best regards. --- ## [About element integrals](https://community.freefem.org/t/about-element-integrals/3032)
**Author:** [@LXX](https://community.freefem.org/u/LXX)\ **Replies:** 1\ **Last updated:** [March 13, 2024, 8:42am UTC](https://community.freefem.org/t/about-element-integrals/3032 "2024-03-13T08:42:14Z")
I want to know how to implement this expression: --- ## ["if" evaluated at compile time](https://community.freefem.org/t/if-evaluated-at-compile-time/2928)
**Author:** [@fb77](https://community.freefem.org/u/fb77)\ **Replies:** 2\ **Last updated:** [February 3, 2024, 2:18pm UTC](https://community.freefem.org/t/if-evaluated-at-compile-time/2928 "2024-02-03T14:18:41Z")
Hello to everybody Is there any way to have an “if” test evaluated at compile time? I would like to have the following type of code to work int n=30; mesh Th=square(n,n); int algo=2; // possible values 1,2,3 if (alg… --- ## [Ndof for composite finite element spaces](https://community.freefem.org/t/ndof-for-composite-finite-element-spaces/2923)
**Author:** [@mhg](https://community.freefem.org/u/mhg)\ **Replies:** 1\ **Last updated:** [February 2, 2024, 3:14pm UTC](https://community.freefem.org/t/ndof-for-composite-finite-element-spaces/2923 "2024-02-02T15:14:03Z")
I cannot compile the following: mesh Th = square(10,10); fespace Vhu(Th, \[P2, P2\]); fespace Vhv(Th, \[P1, P1\]); fespace Ch = Vhu\*Vhv; cout \<\< Ch.ndof \<\< endl; It seems that there is no ndof of a composite finite e… --- ## [Raviart Thomas space of order greater than 2](https://community.freefem.org/t/raviart-thomas-space-of-order-greater-than-2/2732)
**Author:** [@larismartins](https://community.freefem.org/u/larismartins)\ **Replies:** 1\ **Last updated:** [October 4, 2023, 8:02pm UTC](https://community.freefem.org/t/raviart-thomas-space-of-order-greater-than-2/2732 "2023-10-04T20:02:57Z")
Hi guys! I was wondering if there is something in the works for FreeFem++ being able to process Raviart Thomas spaces of orders greater than 2? [Next page](https://community.freefem.org/c/features-request/6.md?page=1)