1c4762a1bSJed Brown! 2*42ce371bSBarry Smith! This example shows how to avoid Fortran line lengths larger than 132 characters. 3*42ce371bSBarry Smith! We recommend starting from src/snes/tutorials/ex5f90.F90 instead of this example 4*42ce371bSBarry Smith! 5c4762a1bSJed Brown! Description: This example solves a nonlinear system in parallel with SNES. 6c4762a1bSJed Brown! We solve the Bratu (SFI - solid fuel ignition) problem in a 2D rectangular 7c4762a1bSJed Brown! domain, using distributed arrays (DMDAs) to partition the parallel grid. 8c4762a1bSJed Brown! The command line options include: 9c4762a1bSJed Brown! -par <param>, where <param> indicates the nonlinearity of the problem 10c4762a1bSJed Brown! problem SFI: <parameter> = Bratu parameter (0 <= par <= 6.81) 11c4762a1bSJed Brown! 12c4762a1bSJed Brown! -------------------------------------------------------------------------- 13c4762a1bSJed Brown! 14c4762a1bSJed Brown! Solid Fuel Ignition (SFI) problem. This problem is modeled by 15c4762a1bSJed Brown! the partial differential equation 16c4762a1bSJed Brown! 17c4762a1bSJed Brown! -Laplacian u - lambda*exp(u) = 0, 0 < x,y < 1, 18c4762a1bSJed Brown! 19c4762a1bSJed Brown! with boundary conditions 20c4762a1bSJed Brown! 21c4762a1bSJed Brown! u = 0 for x = 0, x = 1, y = 0, y = 1. 22c4762a1bSJed Brown! 23c4762a1bSJed Brown! A finite difference approximation with the usual 5-point stencil 24c4762a1bSJed Brown! is used to discretize the boundary value problem to obtain a nonlinear 25c4762a1bSJed Brown! system of equations. 26c4762a1bSJed Brown! 27c4762a1bSJed Brown! -------------------------------------------------------------------------- 28dfbbaf82SBarry Smith module ex5fmodule 29dfbbaf82SBarry Smith use petscsnes 30dfbbaf82SBarry Smith use petscdmda 31dfbbaf82SBarry Smith#include <petsc/finclude/petscsnes.h> 32dfbbaf82SBarry Smith#include <petsc/finclude/petscdm.h> 33dfbbaf82SBarry Smith#include <petsc/finclude/petscdmda.h> 34dfbbaf82SBarry Smith PetscInt xs,xe,xm,gxs,gxe,gxm 35dfbbaf82SBarry Smith PetscInt ys,ye,ym,gys,gye,gym 36dfbbaf82SBarry Smith PetscInt mx,my 37dfbbaf82SBarry Smith PetscMPIInt rank,size 38dfbbaf82SBarry Smith PetscReal lambda 39dfbbaf82SBarry Smith end module ex5fmodule 40c4762a1bSJed Brown 41c4762a1bSJed Brown program main 42dfbbaf82SBarry Smith use ex5fmodule 43c4762a1bSJed Brown implicit none 44c4762a1bSJed Brown 45c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 46c4762a1bSJed Brown! Variable declarations 47c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 48c4762a1bSJed Brown! 49c4762a1bSJed Brown! Variables: 50c4762a1bSJed Brown! snes - nonlinear solver 51c4762a1bSJed Brown! x, r - solution, residual vectors 52c4762a1bSJed Brown! its - iterations for convergence 53c4762a1bSJed Brown! 54c4762a1bSJed Brown! See additional variable declarations in the file ex5f.h 55c4762a1bSJed Brown! 56c4762a1bSJed Brown SNES snes 57c4762a1bSJed Brown Vec x,r 58c4762a1bSJed Brown PetscInt its,i1,i4 59c4762a1bSJed Brown PetscErrorCode ierr 60c4762a1bSJed Brown PetscReal lambda_max,lambda_min 61c4762a1bSJed Brown PetscBool flg 62c4762a1bSJed Brown DM da 63c4762a1bSJed Brown 64c4762a1bSJed Brown! Note: Any user-defined Fortran routines (such as FormJacobianLocal) 65c4762a1bSJed Brown! MUST be declared as external. 66c4762a1bSJed Brown 67c4762a1bSJed Brown external FormInitialGuess 68c4762a1bSJed Brown external FormFunctionLocal,FormJacobianLocal 69c4762a1bSJed Brown external MySNESConverged 70c4762a1bSJed Brown 71c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 72c4762a1bSJed Brown! Initialize program 73c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 74c4762a1bSJed Brown 7565afa91aSSatish Balay call PetscInitialize(ierr) 7665afa91aSSatish Balay CHKERRA(ierr) 7765afa91aSSatish Balay call MPI_Comm_size(PETSC_COMM_WORLD,size,ierr) 7865afa91aSSatish Balay CHKERRMPIA(ierr) 7965afa91aSSatish Balay call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr) 8065afa91aSSatish Balay CHKERRMPIA(ierr) 81c4762a1bSJed Brown! Initialize problem parameters 82c4762a1bSJed Brown 83c4762a1bSJed Brown i1 = 1 84c4762a1bSJed Brown i4 = 4 85c4762a1bSJed Brown lambda_max = 6.81 86c4762a1bSJed Brown lambda_min = 0.0 87c4762a1bSJed Brown lambda = 6.0 8865afa91aSSatish Balay call PetscOptionsGetReal(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-par',lambda,PETSC_NULL_BOOL,ierr) 8965afa91aSSatish Balay CHKERRA(ierr) 9065afa91aSSatish Balay 91c4762a1bSJed Brown! this statement is split into multiple-lines to keep lines under 132 char limit - required by 'make check' 92c4762a1bSJed Brown if (lambda .ge. lambda_max .or. lambda .le. lambda_min) then 93c4762a1bSJed Brown ierr = PETSC_ERR_ARG_OUTOFRANGE; SETERRA(PETSC_COMM_WORLD,ierr,'Lambda') 94c4762a1bSJed Brown endif 95c4762a1bSJed Brown 96c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 97c4762a1bSJed Brown! Create nonlinear solver context 98c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 99c4762a1bSJed Brown 10065afa91aSSatish Balay call SNESCreate(PETSC_COMM_WORLD,snes,ierr) 10165afa91aSSatish Balay CHKERRA(ierr) 102c4762a1bSJed Brown 103c4762a1bSJed Brown! Set convergence test routine if desired 104c4762a1bSJed Brown 10565afa91aSSatish Balay call PetscOptionsHasName(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-my_snes_convergence',flg,ierr) 10665afa91aSSatish Balay CHKERRA(ierr) 107c4762a1bSJed Brown if (flg) then 10865afa91aSSatish Balay call SNESSetConvergenceTest(snes,MySNESConverged,0,PETSC_NULL_FUNCTION,ierr) 10965afa91aSSatish Balay CHKERRA(ierr) 110c4762a1bSJed Brown endif 111c4762a1bSJed Brown 112c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 113c4762a1bSJed Brown! Create vector data structures; set function evaluation routine 114c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 115c4762a1bSJed Brown 116c4762a1bSJed Brown! Create distributed array (DMDA) to manage parallel grid and vectors 117c4762a1bSJed Brown 118*42ce371bSBarry Smith! This really needs only the star-type stencil, but we use the box stencil 11960cf0239SBarry Smith 12065afa91aSSatish Balay call DMDACreate2d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,i4,i4,PETSC_DECIDE,PETSC_DECIDE, & 12165afa91aSSatish Balay i1,i1, PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,da,ierr) 12265afa91aSSatish Balay CHKERRA(ierr) 12365afa91aSSatish Balay call DMSetFromOptions(da,ierr) 12465afa91aSSatish Balay CHKERRA(ierr) 12565afa91aSSatish Balay call DMSetUp(da,ierr) 12665afa91aSSatish Balay CHKERRA(ierr) 127c4762a1bSJed Brown 128c4762a1bSJed Brown! Extract global and local vectors from DMDA; then duplicate for remaining 129c4762a1bSJed Brown! vectors that are the same types 130c4762a1bSJed Brown 13165afa91aSSatish Balay call DMCreateGlobalVector(da,x,ierr) 13265afa91aSSatish Balay CHKERRA(ierr) 13365afa91aSSatish Balay call VecDuplicate(x,r,ierr) 13465afa91aSSatish Balay CHKERRA(ierr) 135c4762a1bSJed Brown 136c4762a1bSJed Brown! Get local grid boundaries (for 2-dimensional DMDA) 137c4762a1bSJed Brown 13860cf0239SBarry Smith call DMDAGetInfo(da,PETSC_NULL_INTEGER,mx,my,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER, & 13960cf0239SBarry Smith PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER, & 14060cf0239SBarry Smith PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,ierr) 14165afa91aSSatish Balay CHKERRA(ierr) 14265afa91aSSatish Balay call DMDAGetCorners(da,xs,ys,PETSC_NULL_INTEGER,xm,ym,PETSC_NULL_INTEGER,ierr) 14365afa91aSSatish Balay CHKERRA(ierr) 14465afa91aSSatish Balay call DMDAGetGhostCorners(da,gxs,gys,PETSC_NULL_INTEGER,gxm,gym,PETSC_NULL_INTEGER,ierr) 14565afa91aSSatish Balay CHKERRA(ierr) 146c4762a1bSJed Brown 147c4762a1bSJed Brown! Here we shift the starting indices up by one so that we can easily 148c4762a1bSJed Brown! use the Fortran convention of 1-based indices (rather 0-based indices). 149c4762a1bSJed Brown 150c4762a1bSJed Brown xs = xs+1 151c4762a1bSJed Brown ys = ys+1 152c4762a1bSJed Brown gxs = gxs+1 153c4762a1bSJed Brown gys = gys+1 154c4762a1bSJed Brown 155c4762a1bSJed Brown ye = ys+ym-1 156c4762a1bSJed Brown xe = xs+xm-1 157c4762a1bSJed Brown gye = gys+gym-1 158c4762a1bSJed Brown gxe = gxs+gxm-1 159c4762a1bSJed Brown 160c4762a1bSJed Brown! Set function evaluation routine and vector 161c4762a1bSJed Brown 16265afa91aSSatish Balay call DMDASNESSetFunctionLocal(da,INSERT_VALUES,FormFunctionLocal,da,ierr) 16365afa91aSSatish Balay CHKERRA(ierr) 16465afa91aSSatish Balay call DMDASNESSetJacobianLocal(da,FormJacobianLocal,da,ierr) 16565afa91aSSatish Balay CHKERRA(ierr) 16665afa91aSSatish Balay call SNESSetDM(snes,da,ierr) 16765afa91aSSatish Balay CHKERRA(ierr) 168c4762a1bSJed Brown 169c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 170c4762a1bSJed Brown! Customize nonlinear solver; set runtime options 171c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 172c4762a1bSJed Brown 173c4762a1bSJed Brown! Set runtime options (e.g., -snes_monitor -snes_rtol <rtol> -ksp_type <type>) 174c4762a1bSJed Brown 17565afa91aSSatish Balay call SNESSetFromOptions(snes,ierr) 17665afa91aSSatish Balay CHKERRA(ierr) 177c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 178c4762a1bSJed Brown! Evaluate initial guess; then solve nonlinear system. 179c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 180c4762a1bSJed Brown 181c4762a1bSJed Brown! Note: The user should initialize the vector, x, with the initial guess 182c4762a1bSJed Brown! for the nonlinear solver prior to calling SNESSolve(). In particular, 183c4762a1bSJed Brown! to employ an initial guess of zero, the user should explicitly set 184c4762a1bSJed Brown! this vector to zero by calling VecSet(). 185c4762a1bSJed Brown 18665afa91aSSatish Balay call FormInitialGuess(x,ierr) 18765afa91aSSatish Balay CHKERRA(ierr) 18865afa91aSSatish Balay call SNESSolve(snes,PETSC_NULL_VEC,x,ierr) 18965afa91aSSatish Balay CHKERRA(ierr) 19065afa91aSSatish Balay call SNESGetIterationNumber(snes,its,ierr) 19165afa91aSSatish Balay CHKERRA(ierr) 192c4762a1bSJed Brown if (rank .eq. 0) then 193c4762a1bSJed Brown write(6,100) its 194c4762a1bSJed Brown endif 195c4762a1bSJed Brown 100 format('Number of SNES iterations = ',i5) 196c4762a1bSJed Brown 197c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 198c4762a1bSJed Brown! Free work space. All PETSc objects should be destroyed when they 199c4762a1bSJed Brown! are no longer needed. 200c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 201c4762a1bSJed Brown 20265afa91aSSatish Balay call VecDestroy(x,ierr) 20365afa91aSSatish Balay CHKERRA(ierr) 20465afa91aSSatish Balay call VecDestroy(r,ierr) 20565afa91aSSatish Balay CHKERRA(ierr) 20665afa91aSSatish Balay call SNESDestroy(snes,ierr) 20765afa91aSSatish Balay CHKERRA(ierr) 20865afa91aSSatish Balay call DMDestroy(da,ierr) 20965afa91aSSatish Balay CHKERRA(ierr) 21065afa91aSSatish Balay call PetscFinalize(ierr) 21165afa91aSSatish Balay CHKERRA(ierr) 212c4762a1bSJed Brown end 213c4762a1bSJed Brown 214c4762a1bSJed Brown! --------------------------------------------------------------------- 215c4762a1bSJed Brown! 216c4762a1bSJed Brown! FormInitialGuess - Forms initial approximation. 217c4762a1bSJed Brown! 218c4762a1bSJed Brown! Input Parameters: 219c4762a1bSJed Brown! X - vector 220c4762a1bSJed Brown! 221c4762a1bSJed Brown! Output Parameter: 222c4762a1bSJed Brown! X - vector 223c4762a1bSJed Brown! 224c4762a1bSJed Brown! Notes: 225c4762a1bSJed Brown! This routine serves as a wrapper for the lower-level routine 226c4762a1bSJed Brown! "ApplicationInitialGuess", where the actual computations are 227c4762a1bSJed Brown! done using the standard Fortran style of treating the local 228c4762a1bSJed Brown! vector data as a multidimensional array over the local mesh. 229c4762a1bSJed Brown! This routine merely handles ghost point scatters and accesses 230*42ce371bSBarry Smith! the local vector data via VecGetArrayF90() and VecRestoreArrayF90(). 231c4762a1bSJed Brown! 232c4762a1bSJed Brown subroutine FormInitialGuess(X,ierr) 233dfbbaf82SBarry Smith use ex5fmodule 234c4762a1bSJed Brown implicit none 235c4762a1bSJed Brown 236c4762a1bSJed Brown! Input/output variables: 237c4762a1bSJed Brown Vec X 238c4762a1bSJed Brown PetscErrorCode ierr 239c4762a1bSJed Brown! Declarations for use with local arrays: 240*42ce371bSBarry Smith PetscScalar, pointer :: lx_v(:) 241c4762a1bSJed Brown 242c4762a1bSJed Brown ierr = 0 243c4762a1bSJed Brown 244c4762a1bSJed Brown! Get a pointer to vector data. 245c4762a1bSJed Brown! - For default PETSc vectors, VecGetArray() returns a pointer to 246c4762a1bSJed Brown! the data array. Otherwise, the routine is implementation dependent. 247c4762a1bSJed Brown! - You MUST call VecRestoreArray() when you no longer need access to 248c4762a1bSJed Brown! the array. 249c4762a1bSJed Brown! - Note that the Fortran interface to VecGetArray() differs from the 250c4762a1bSJed Brown! C version. See the users manual for details. 251c4762a1bSJed Brown 252*42ce371bSBarry Smith call VecGetArrayF90(X,lx_v,ierr) 25365afa91aSSatish Balay CHKERRQ(ierr) 254c4762a1bSJed Brown 255c4762a1bSJed Brown! Compute initial guess over the locally owned part of the grid 256c4762a1bSJed Brown 257*42ce371bSBarry Smith call InitialGuessLocal(lx_v,ierr) 25865afa91aSSatish Balay CHKERRQ(ierr) 259c4762a1bSJed Brown 260c4762a1bSJed Brown! Restore vector 261c4762a1bSJed Brown 262*42ce371bSBarry Smith call VecRestoreArrayF90(X,lx_v,ierr) 26365afa91aSSatish Balay CHKERRQ(ierr) 264c4762a1bSJed Brown 265c4762a1bSJed Brown return 266c4762a1bSJed Brown end 267c4762a1bSJed Brown 268c4762a1bSJed Brown! --------------------------------------------------------------------- 269c4762a1bSJed Brown! 270c4762a1bSJed Brown! InitialGuessLocal - Computes initial approximation, called by 271c4762a1bSJed Brown! the higher level routine FormInitialGuess(). 272c4762a1bSJed Brown! 273c4762a1bSJed Brown! Input Parameter: 274c4762a1bSJed Brown! x - local vector data 275c4762a1bSJed Brown! 276c4762a1bSJed Brown! Output Parameters: 277c4762a1bSJed Brown! x - local vector data 278c4762a1bSJed Brown! ierr - error code 279c4762a1bSJed Brown! 280c4762a1bSJed Brown! Notes: 281c4762a1bSJed Brown! This routine uses standard Fortran-style computations over a 2-dim array. 282c4762a1bSJed Brown! 283c4762a1bSJed Brown subroutine InitialGuessLocal(x,ierr) 284dfbbaf82SBarry Smith use ex5fmodule 285c4762a1bSJed Brown implicit none 286c4762a1bSJed Brown 287c4762a1bSJed Brown! Input/output variables: 288c4762a1bSJed Brown PetscScalar x(xs:xe,ys:ye) 289c4762a1bSJed Brown PetscErrorCode ierr 290c4762a1bSJed Brown 291c4762a1bSJed Brown! Local variables: 292c4762a1bSJed Brown PetscInt i,j 293c4762a1bSJed Brown PetscReal temp1,temp,one,hx,hy 294c4762a1bSJed Brown 295c4762a1bSJed Brown! Set parameters 296c4762a1bSJed Brown 297c4762a1bSJed Brown ierr = 0 298c4762a1bSJed Brown one = 1.0 299c4762a1bSJed Brown hx = one/((mx-1)) 300c4762a1bSJed Brown hy = one/((my-1)) 301c4762a1bSJed Brown temp1 = lambda/(lambda + one) 302c4762a1bSJed Brown 303c4762a1bSJed Brown do 20 j=ys,ye 304c4762a1bSJed Brown temp = (min(j-1,my-j))*hy 305c4762a1bSJed Brown do 10 i=xs,xe 306c4762a1bSJed Brown if (i .eq. 1 .or. j .eq. 1 .or. i .eq. mx .or. j .eq. my) then 307c4762a1bSJed Brown x(i,j) = 0.0 308c4762a1bSJed Brown else 309c4762a1bSJed Brown x(i,j) = temp1 * sqrt(min(min(i-1,mx-i)*hx,(temp))) 310c4762a1bSJed Brown endif 311c4762a1bSJed Brown 10 continue 312c4762a1bSJed Brown 20 continue 313c4762a1bSJed Brown 314c4762a1bSJed Brown return 315c4762a1bSJed Brown end 316c4762a1bSJed Brown 317c4762a1bSJed Brown! --------------------------------------------------------------------- 318c4762a1bSJed Brown! 319c4762a1bSJed Brown! FormFunctionLocal - Computes nonlinear function, called by 320c4762a1bSJed Brown! the higher level routine FormFunction(). 321c4762a1bSJed Brown! 322c4762a1bSJed Brown! Input Parameter: 323c4762a1bSJed Brown! x - local vector data 324c4762a1bSJed Brown! 325c4762a1bSJed Brown! Output Parameters: 326c4762a1bSJed Brown! f - local vector data, f(x) 327c4762a1bSJed Brown! ierr - error code 328c4762a1bSJed Brown! 329c4762a1bSJed Brown! Notes: 330c4762a1bSJed Brown! This routine uses standard Fortran-style computations over a 2-dim array. 331c4762a1bSJed Brown! 332c4762a1bSJed Brown! 333c4762a1bSJed Brown subroutine FormFunctionLocal(info,x,f,da,ierr) 334dfbbaf82SBarry Smith use ex5fmodule 335c4762a1bSJed Brown implicit none 336c4762a1bSJed Brown 337c4762a1bSJed Brown DM da 338c4762a1bSJed Brown 339c4762a1bSJed Brown! Input/output variables: 340c4762a1bSJed Brown DMDALocalInfo info(DMDA_LOCAL_INFO_SIZE) 341c4762a1bSJed Brown PetscScalar x(gxs:gxe,gys:gye) 342c4762a1bSJed Brown PetscScalar f(xs:xe,ys:ye) 343c4762a1bSJed Brown PetscErrorCode ierr 344c4762a1bSJed Brown 345c4762a1bSJed Brown! Local variables: 346c4762a1bSJed Brown PetscScalar two,one,hx,hy 347c4762a1bSJed Brown PetscScalar hxdhy,hydhx,sc 348c4762a1bSJed Brown PetscScalar u,uxx,uyy 349c4762a1bSJed Brown PetscInt i,j 350c4762a1bSJed Brown 351c4762a1bSJed Brown xs = info(DMDA_LOCAL_INFO_XS)+1 352c4762a1bSJed Brown xe = xs+info(DMDA_LOCAL_INFO_XM)-1 353c4762a1bSJed Brown ys = info(DMDA_LOCAL_INFO_YS)+1 354c4762a1bSJed Brown ye = ys+info(DMDA_LOCAL_INFO_YM)-1 355c4762a1bSJed Brown mx = info(DMDA_LOCAL_INFO_MX) 356c4762a1bSJed Brown my = info(DMDA_LOCAL_INFO_MY) 357c4762a1bSJed Brown 358c4762a1bSJed Brown one = 1.0 359c4762a1bSJed Brown two = 2.0 360c4762a1bSJed Brown hx = one/(mx-1) 361c4762a1bSJed Brown hy = one/(my-1) 362c4762a1bSJed Brown sc = hx*hy*lambda 363c4762a1bSJed Brown hxdhy = hx/hy 364c4762a1bSJed Brown hydhx = hy/hx 365c4762a1bSJed Brown 366c4762a1bSJed Brown! Compute function over the locally owned part of the grid 367c4762a1bSJed Brown 368c4762a1bSJed Brown do 20 j=ys,ye 369c4762a1bSJed Brown do 10 i=xs,xe 370c4762a1bSJed Brown if (i .eq. 1 .or. j .eq. 1 .or. i .eq. mx .or. j .eq. my) then 371c4762a1bSJed Brown f(i,j) = x(i,j) 372c4762a1bSJed Brown else 373c4762a1bSJed Brown u = x(i,j) 374c4762a1bSJed Brown uxx = hydhx * (two*u - x(i-1,j) - x(i+1,j)) 375c4762a1bSJed Brown uyy = hxdhy * (two*u - x(i,j-1) - x(i,j+1)) 376c4762a1bSJed Brown f(i,j) = uxx + uyy - sc*exp(u) 377c4762a1bSJed Brown endif 378c4762a1bSJed Brown 10 continue 379c4762a1bSJed Brown 20 continue 380c4762a1bSJed Brown 38165afa91aSSatish Balay call PetscLogFlops(11.0d0*ym*xm,ierr) 38265afa91aSSatish Balay CHKERRQ(ierr) 383c4762a1bSJed Brown 384c4762a1bSJed Brown return 385c4762a1bSJed Brown end 386c4762a1bSJed Brown 387c4762a1bSJed Brown! --------------------------------------------------------------------- 388c4762a1bSJed Brown! 389c4762a1bSJed Brown! FormJacobianLocal - Computes Jacobian matrix, called by 390c4762a1bSJed Brown! the higher level routine FormJacobian(). 391c4762a1bSJed Brown! 392c4762a1bSJed Brown! Input Parameters: 393c4762a1bSJed Brown! x - local vector data 394c4762a1bSJed Brown! 395c4762a1bSJed Brown! Output Parameters: 396c4762a1bSJed Brown! jac - Jacobian matrix 397c4762a1bSJed Brown! jac_prec - optionally different preconditioning matrix (not used here) 398c4762a1bSJed Brown! ierr - error code 399c4762a1bSJed Brown! 400c4762a1bSJed Brown! Notes: 401c4762a1bSJed Brown! This routine uses standard Fortran-style computations over a 2-dim array. 402c4762a1bSJed Brown! 403c4762a1bSJed Brown! Notes: 404c4762a1bSJed Brown! Due to grid point reordering with DMDAs, we must always work 405c4762a1bSJed Brown! with the local grid points, and then transform them to the new 406c4762a1bSJed Brown! global numbering with the "ltog" mapping 407c4762a1bSJed Brown! We cannot work directly with the global numbers for the original 408c4762a1bSJed Brown! uniprocessor grid! 409c4762a1bSJed Brown! 410c4762a1bSJed Brown! Two methods are available for imposing this transformation 411c4762a1bSJed Brown! when setting matrix entries: 412c4762a1bSJed Brown! (A) MatSetValuesLocal(), using the local ordering (including 413c4762a1bSJed Brown! ghost points!) 414c4762a1bSJed Brown! by calling MatSetValuesLocal() 415c4762a1bSJed Brown! (B) MatSetValues(), using the global ordering 416c4762a1bSJed Brown! - Use DMDAGetGlobalIndices() to extract the local-to-global map 417c4762a1bSJed Brown! - Then apply this map explicitly yourself 418c4762a1bSJed Brown! - Set matrix entries using the global ordering by calling 419c4762a1bSJed Brown! MatSetValues() 420c4762a1bSJed Brown! Option (A) seems cleaner/easier in many cases, and is the procedure 421c4762a1bSJed Brown! used in this example. 422c4762a1bSJed Brown! 423c4762a1bSJed Brown subroutine FormJacobianLocal(info,x,A,jac,da,ierr) 424dfbbaf82SBarry Smith use ex5fmodule 425c4762a1bSJed Brown implicit none 426c4762a1bSJed Brown 427c4762a1bSJed Brown DM da 428c4762a1bSJed Brown 429c4762a1bSJed Brown! Input/output variables: 430c4762a1bSJed Brown PetscScalar x(gxs:gxe,gys:gye) 431c4762a1bSJed Brown Mat A,jac 432c4762a1bSJed Brown PetscErrorCode ierr 433c4762a1bSJed Brown DMDALocalInfo info(DMDA_LOCAL_INFO_SIZE) 434c4762a1bSJed Brown 435c4762a1bSJed Brown! Local variables: 436c4762a1bSJed Brown PetscInt row,col(5),i,j,i1,i5 437c4762a1bSJed Brown PetscScalar two,one,hx,hy,v(5) 438c4762a1bSJed Brown PetscScalar hxdhy,hydhx,sc 439c4762a1bSJed Brown 440c4762a1bSJed Brown! Set parameters 441c4762a1bSJed Brown 442c4762a1bSJed Brown i1 = 1 443c4762a1bSJed Brown i5 = 5 444c4762a1bSJed Brown one = 1.0 445c4762a1bSJed Brown two = 2.0 446c4762a1bSJed Brown hx = one/(mx-1) 447c4762a1bSJed Brown hy = one/(my-1) 448c4762a1bSJed Brown sc = hx*hy 449c4762a1bSJed Brown hxdhy = hx/hy 450c4762a1bSJed Brown hydhx = hy/hx 451c4762a1bSJed Brown 452c4762a1bSJed Brown! Compute entries for the locally owned part of the Jacobian. 453c4762a1bSJed Brown! - Currently, all PETSc parallel matrix formats are partitioned by 454c4762a1bSJed Brown! contiguous chunks of rows across the processors. 455c4762a1bSJed Brown! - Each processor needs to insert only elements that it owns 456c4762a1bSJed Brown! locally (but any non-local elements will be sent to the 457c4762a1bSJed Brown! appropriate processor during matrix assembly). 458c4762a1bSJed Brown! - Here, we set all entries for a particular row at once. 459c4762a1bSJed Brown! - We can set matrix entries either using either 460c4762a1bSJed Brown! MatSetValuesLocal() or MatSetValues(), as discussed above. 461c4762a1bSJed Brown! - Note that MatSetValues() uses 0-based row and column numbers 462c4762a1bSJed Brown! in Fortran as well as in C. 463c4762a1bSJed Brown 464c4762a1bSJed Brown do 20 j=ys,ye 465c4762a1bSJed Brown row = (j - gys)*gxm + xs - gxs - 1 466c4762a1bSJed Brown do 10 i=xs,xe 467c4762a1bSJed Brown row = row + 1 468c4762a1bSJed Brown! boundary points 469c4762a1bSJed Brown if (i .eq. 1 .or. j .eq. 1 .or. i .eq. mx .or. j .eq. my) then 470c4762a1bSJed Brown! Some f90 compilers need 4th arg to be of same type in both calls 471c4762a1bSJed Brown col(1) = row 472c4762a1bSJed Brown v(1) = one 47365afa91aSSatish Balay call MatSetValuesLocal(jac,i1,row,i1,col,v,INSERT_VALUES,ierr) 47465afa91aSSatish Balay CHKERRQ(ierr) 475c4762a1bSJed Brown! interior grid points 476c4762a1bSJed Brown else 477c4762a1bSJed Brown v(1) = -hxdhy 478c4762a1bSJed Brown v(2) = -hydhx 479c4762a1bSJed Brown v(3) = two*(hydhx + hxdhy) - sc*lambda*exp(x(i,j)) 480c4762a1bSJed Brown v(4) = -hydhx 481c4762a1bSJed Brown v(5) = -hxdhy 482c4762a1bSJed Brown col(1) = row - gxm 483c4762a1bSJed Brown col(2) = row - 1 484c4762a1bSJed Brown col(3) = row 485c4762a1bSJed Brown col(4) = row + 1 486c4762a1bSJed Brown col(5) = row + gxm 48765afa91aSSatish Balay call MatSetValuesLocal(jac,i1,row,i5,col,v, INSERT_VALUES,ierr) 48865afa91aSSatish Balay CHKERRQ(ierr) 489c4762a1bSJed Brown endif 490c4762a1bSJed Brown 10 continue 491c4762a1bSJed Brown 20 continue 49265afa91aSSatish Balay call MatAssemblyBegin(jac,MAT_FINAL_ASSEMBLY,ierr) 49365afa91aSSatish Balay CHKERRQ(ierr) 49465afa91aSSatish Balay call MatAssemblyEnd(jac,MAT_FINAL_ASSEMBLY,ierr) 49565afa91aSSatish Balay CHKERRQ(ierr) 496c4762a1bSJed Brown if (A .ne. jac) then 49765afa91aSSatish Balay call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY,ierr) 49865afa91aSSatish Balay CHKERRQ(ierr) 49965afa91aSSatish Balay call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY,ierr) 50065afa91aSSatish Balay CHKERRQ(ierr) 501c4762a1bSJed Brown endif 502c4762a1bSJed Brown return 503c4762a1bSJed Brown end 504c4762a1bSJed Brown 505c4762a1bSJed Brown! 506c4762a1bSJed Brown! Simple convergence test based on the infinity norm of the residual being small 507c4762a1bSJed Brown! 508c4762a1bSJed Brown subroutine MySNESConverged(snes,it,xnorm,snorm,fnorm,reason,dummy,ierr) 509dfbbaf82SBarry Smith use ex5fmodule 510c4762a1bSJed Brown implicit none 511c4762a1bSJed Brown 512c4762a1bSJed Brown SNES snes 513c4762a1bSJed Brown PetscInt it,dummy 514c4762a1bSJed Brown PetscReal xnorm,snorm,fnorm,nrm 515c4762a1bSJed Brown SNESConvergedReason reason 516c4762a1bSJed Brown Vec f 517c4762a1bSJed Brown PetscErrorCode ierr 518c4762a1bSJed Brown 51965afa91aSSatish Balay call SNESGetFunction(snes,f,PETSC_NULL_FUNCTION,dummy,ierr) 52065afa91aSSatish Balay CHKERRQ(ierr) 52165afa91aSSatish Balay call VecNorm(f,NORM_INFINITY,nrm,ierr) 52265afa91aSSatish Balay CHKERRQ(ierr) 523c4762a1bSJed Brown if (nrm .le. 1.e-5) reason = SNES_CONVERGED_FNORM_ABS 524c4762a1bSJed Brown 525c4762a1bSJed Brown end 526c4762a1bSJed Brown 527c4762a1bSJed Brown!/*TEST 528c4762a1bSJed Brown! 529c4762a1bSJed Brown! build: 530c4762a1bSJed Brown! requires: !complex !single 531c4762a1bSJed Brown! 532c4762a1bSJed Brown! test: 533c4762a1bSJed Brown! nsize: 4 5348f8b3c79SStefano Zampini! args: -snes_mf -pc_type none -da_processors_x 4 -da_processors_y 1 -snes_monitor_short \ 5358f8b3c79SStefano Zampini! -ksp_gmres_cgs_refinement_type refine_always 536c4762a1bSJed Brown! 537c4762a1bSJed Brown! test: 538c4762a1bSJed Brown! suffix: 2 539c4762a1bSJed Brown! nsize: 4 540c4762a1bSJed Brown! args: -da_processors_x 2 -da_processors_y 2 -snes_monitor_short -ksp_gmres_cgs_refinement_type refine_always 541c4762a1bSJed Brown! 542c4762a1bSJed Brown! test: 543c4762a1bSJed Brown! suffix: 3 544c4762a1bSJed Brown! nsize: 3 545c4762a1bSJed Brown! args: -snes_fd -snes_monitor_short -ksp_gmres_cgs_refinement_type refine_always 546c4762a1bSJed Brown! 547c4762a1bSJed Brown! test: 548c4762a1bSJed Brown! suffix: 6 549c4762a1bSJed Brown! nsize: 1 550c4762a1bSJed Brown! args: -snes_monitor_short -my_snes_convergence 551c4762a1bSJed Brown! 552c4762a1bSJed Brown!TEST*/ 553