# Varf including finite element function that is solution of different PDE in parallel computing using PETSc **URL:** \ **Category:** General Discussion\ **Created:** [February 2, 2023, 2:48am UTC](https://community.freefem.org/t/varf-including-finite-element-function-that-is-solution-of-different-pde-in-parallel-computing-using-petsc/2259 "2023-02-02T02:48:37Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Keita](https://avatars.discourse-cdn.com/v4/letter/k/977dab/32.png) [@Keita](https://community.freefem.org/u/Keita)\ **Post date:** [February 2, 2023, 2:48am UTC](https://community.freefem.org/t/varf-including-finite-element-function-that-is-solution-of-different-pde-in-parallel-computing-using-petsc/2259/1 "2023-02-02T02:48:37Z")
Hi FreeFem++ developers! Thank you very much for makingFF. I’d like to perform the 3D topology optimization, where the 3D elasticity problem and reaction-diffusion equation (RDE) are included, using PETSc. There, the structure is represented by characteristic (chi) function obtained by the solution of RDE. At first, I tried this code for parallel computing of 3D elasticity problem as follows: There varf includes chiP that is updated in iterative process during optimization. That chiP is obtained by the RDE (that is not parallel computing) followed by this elasticity problem. * * * ``` load "PETSc" // PETSc plugin macro dimension()3// EOM // 2D or 3D include "macro_ddm.idp" // generate mesh func Pk = [P2, P2, P2]; // finite element space fespace Wh(Sh, Pk); buildDmesh(Sh); Mat A; // following two macros are required in "creatMat" macro def(i)[i, i#B, i#C]// EOM // vector field definition macro init(i)[i, i, i]// EOM // vector field initialization createMat(Sh, A, Pk) Wh def(u); macro epsilon(u) [dx(u),dy(u#B),dz(u#C),(dz(u#B)+dy(u#C)), (dz(u)+dx(u#C)), (dy(u)+dx(u#B))] // strain tensor macro D [ [2.*mu+lambda, lambda, lambda, 0, 0, 0 ], [lambda, 2.*mu+lambda, lambda, 0, 0, 0 ], [lambda, lambda, 2.*mu+lambda, 0, 0, 0 ], [0, 0, 0, mu, 0, 0 ], [0, 0, 0, 0, mu, 0 ], [0, 0, 0, 0, 0, mu ] ] //elastic tensor macro Aotomori [ [2.*A2+A1 , A1, A1, 0, 0, 0 ], [A1, 2.*A2+A1 , A1, 0, 0, 0 ], [A1, A1, 2.*A2+A1 , 0, 0, 0 ], [0, 0, 0, A2 , 0, 0 ], [0, 0, 0, 0 , A2, 0 ], [0, 0, 0, 0 , 0, A2 ] ] //elastic tensor real gZ; gZ = -0.01; macro div(u)(dx(u) + dy(u#B) + dz(u#C))// EOM varf vPb(def(u), def(v)) = int3d(Sh)((D*epsilon(u))'*epsilon(v)*E* chiP ) +int2d(Sh,traction)(gZ*vC) + on(wall, u = 0.0, uB = 0.0, uC = 0.0); A = vPb(Wh, Wh); // define right hand side vector real[int] rhs = vPb(0, Wh); // set solver set(A, sparams = "-pc_type gamg -ksp_view -ksp_max_it 200", bs = 3); // solve u[] = A^-1 * rhs; ``` * * * I don’t have any error, but during optimization process, the change of chiP is not affected when the elasticity is solved. How can I send information about chiP solved in RDE to the parallel solver of the elastic problem ? Sorry if there have been similar questions in the past. I would appreciate your response. ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [February 2, 2023, 7:03am UTC](https://community.freefem.org/t/varf-including-finite-element-function-that-is-solution-of-different-pde-in-parallel-computing-using-petsc/2259/2 "2023-02-02T07:03:02Z")
You did not copy/paste’d your code properly. ---
**Author:** ![Keita](https://avatars.discourse-cdn.com/v4/letter/k/977dab/32.png) [@Keita](https://community.freefem.org/u/Keita)\ **Post date:** [February 2, 2023, 7:22am UTC](https://community.freefem.org/t/varf-including-finite-element-function-that-is-solution-of-different-pde-in-parallel-computing-using-petsc/2259/3 "2023-02-02T07:22:14Z")
Thank you for your reply on your busy schedule. I have sent you a part of the code. Should I send you the code for the entire optimization? I wish there was a way to send it to you hidden. ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [February 2, 2023, 7:27am UTC](https://community.freefem.org/t/varf-including-finite-element-function-that-is-solution-of-different-pde-in-parallel-computing-using-petsc/2259/4 "2023-02-02T07:27:22Z")
You can send it in private. ---
**Author:** ![Keita](https://avatars.discourse-cdn.com/v4/letter/k/977dab/32.png) [@Keita](https://community.freefem.org/u/Keita)\ **Post date:** [February 6, 2023, 1:59am UTC](https://community.freefem.org/t/varf-including-finite-element-function-that-is-solution-of-different-pde-in-parallel-computing-using-petsc/2259/6 "2023-02-06T01:59:32Z")
Dear Professor Jolivet Thank you for consulting with me through personal communication. What I’d like to do is sending the solution, which is computed sequentially, to a segmented region in parallel computing. I have not looked into the official documentation enough and that can be accomplished by using the command as follow: * * * ``` broadcast(processor(int rk), Data D) ``` * * * This means that Process rk Broadcast Data D to all process inside MPI\_COMM\_WORLD. Many thanks, Keita Kambayashi ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [February 6, 2023, 7:18am UTC](https://community.freefem.org/t/varf-including-finite-element-function-that-is-solution-of-different-pde-in-parallel-computing-using-petsc/2259/7 "2023-02-06T07:18:03Z")
Yes, this calls [MPI\_Bcast(3) man page (version 4.1.4)](https://www.open-mpi.org/doc/v4.1/man3/MPI_Bcast.3.php) internally.