1c4762a1bSJed Brown! 242ce371bSBarry Smith! This example shows how to avoid Fortran line lengths larger than 132 characters. 3dcb3e689SBarry Smith! It avoids used of certain macros such as PetscCallA() and PetscCheckA() that 4dcb3e689SBarry Smith! generate very long lines 5dcb3e689SBarry Smith! 642ce371bSBarry Smith! We recommend starting from src/snes/tutorials/ex5f90.F90 instead of this example 7dcb3e689SBarry Smith! because that does not have the restricted formatting that makes this version 8dcb3e689SBarry Smith! more difficult to read 942ce371bSBarry Smith! 10c4762a1bSJed Brown! Description: This example solves a nonlinear system in parallel with SNES. 11c4762a1bSJed Brown! We solve the Bratu (SFI - solid fuel ignition) problem in a 2D rectangular 12c4762a1bSJed Brown! domain, using distributed arrays (DMDAs) to partition the parallel grid. 13c4762a1bSJed Brown! The command line options include: 14c4762a1bSJed Brown! -par <param>, where <param> indicates the nonlinearity of the problem 15c4762a1bSJed Brown! problem SFI: <parameter> = Bratu parameter (0 <= par <= 6.81) 16c4762a1bSJed Brown! 17c4762a1bSJed Brown! -------------------------------------------------------------------------- 18c4762a1bSJed Brown! 19c4762a1bSJed Brown! Solid Fuel Ignition (SFI) problem. This problem is modeled by 20c4762a1bSJed Brown! the partial differential equation 21c4762a1bSJed Brown! 22c4762a1bSJed Brown! -Laplacian u - lambda*exp(u) = 0, 0 < x,y < 1, 23c4762a1bSJed Brown! 24c4762a1bSJed Brown! with boundary conditions 25c4762a1bSJed Brown! 26c4762a1bSJed Brown! u = 0 for x = 0, x = 1, y = 0, y = 1. 27c4762a1bSJed Brown! 28c4762a1bSJed Brown! A finite difference approximation with the usual 5-point stencil 29c4762a1bSJed Brown! is used to discretize the boundary value problem to obtain a nonlinear 30c4762a1bSJed Brown! system of equations. 31c4762a1bSJed Brown! 32c4762a1bSJed Brown! -------------------------------------------------------------------------- 33dfbbaf82SBarry Smith module ex5fmodule 34dfbbaf82SBarry Smith use petscsnes 35dfbbaf82SBarry Smith use petscdmda 36dfbbaf82SBarry Smith#include <petsc/finclude/petscsnes.h> 37dfbbaf82SBarry Smith#include <petsc/finclude/petscdmda.h> 38dfbbaf82SBarry Smith PetscInt xs,xe,xm,gxs,gxe,gxm 39dfbbaf82SBarry Smith PetscInt ys,ye,ym,gys,gye,gym 40dfbbaf82SBarry Smith PetscInt mx,my 41dfbbaf82SBarry Smith PetscMPIInt rank,size 42dfbbaf82SBarry Smith PetscReal lambda 43dfbbaf82SBarry Smith end module ex5fmodule 44c4762a1bSJed Brown 45c4762a1bSJed Brown program main 46dfbbaf82SBarry Smith use ex5fmodule 47c4762a1bSJed Brown implicit none 48c4762a1bSJed Brown 49c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 50c4762a1bSJed Brown! Variable declarations 51c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 52c4762a1bSJed Brown! 53c4762a1bSJed Brown! Variables: 54c4762a1bSJed Brown! snes - nonlinear solver 55c4762a1bSJed Brown! x, r - solution, residual vectors 56c4762a1bSJed Brown! its - iterations for convergence 57c4762a1bSJed Brown! 58c4762a1bSJed Brown! See additional variable declarations in the file ex5f.h 59c4762a1bSJed Brown! 60c4762a1bSJed Brown SNES snes 61c4762a1bSJed Brown Vec x,r 62c4762a1bSJed Brown PetscInt its,i1,i4 63c4762a1bSJed Brown PetscErrorCode ierr 64c4762a1bSJed Brown PetscReal lambda_max,lambda_min 65c4762a1bSJed Brown PetscBool flg 66c4762a1bSJed Brown DM da 67c4762a1bSJed Brown 68c4762a1bSJed Brown! Note: Any user-defined Fortran routines (such as FormJacobianLocal) 69c4762a1bSJed Brown! MUST be declared as external. 70c4762a1bSJed Brown 71c4762a1bSJed Brown external FormInitialGuess 72c4762a1bSJed Brown external FormFunctionLocal,FormJacobianLocal 73c4762a1bSJed Brown external MySNESConverged 74c4762a1bSJed Brown 75c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 76c4762a1bSJed Brown! Initialize program 77c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 78c4762a1bSJed Brown 7965afa91aSSatish Balay call PetscInitialize(ierr) 8065afa91aSSatish Balay CHKERRA(ierr) 8165afa91aSSatish Balay call MPI_Comm_size(PETSC_COMM_WORLD,size,ierr) 8265afa91aSSatish Balay CHKERRMPIA(ierr) 8365afa91aSSatish Balay call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr) 8465afa91aSSatish Balay CHKERRMPIA(ierr) 85c4762a1bSJed Brown! Initialize problem parameters 86c4762a1bSJed Brown 87c4762a1bSJed Brown i1 = 1 88c4762a1bSJed Brown i4 = 4 89c4762a1bSJed Brown lambda_max = 6.81 90c4762a1bSJed Brown lambda_min = 0.0 91c4762a1bSJed Brown lambda = 6.0 9265afa91aSSatish Balay call PetscOptionsGetReal(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-par',lambda,PETSC_NULL_BOOL,ierr) 9365afa91aSSatish Balay CHKERRA(ierr) 9465afa91aSSatish Balay 95c4762a1bSJed Brown! this statement is split into multiple-lines to keep lines under 132 char limit - required by 'make check' 96c4762a1bSJed Brown if (lambda .ge. lambda_max .or. lambda .le. lambda_min) then 97*ccfd86f1SBarry Smith ierr = PETSC_ERR_ARG_OUTOFRANGE 98dcb3e689SBarry Smith SETERRA(PETSC_COMM_WORLD,ierr,'Lambda') 99c4762a1bSJed Brown endif 100c4762a1bSJed Brown 101c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 102c4762a1bSJed Brown! Create nonlinear solver context 103c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 104c4762a1bSJed Brown 10565afa91aSSatish Balay call SNESCreate(PETSC_COMM_WORLD,snes,ierr) 10665afa91aSSatish Balay CHKERRA(ierr) 107c4762a1bSJed Brown 108c4762a1bSJed Brown! Set convergence test routine if desired 109c4762a1bSJed Brown 11065afa91aSSatish Balay call PetscOptionsHasName(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-my_snes_convergence',flg,ierr) 11165afa91aSSatish Balay CHKERRA(ierr) 112c4762a1bSJed Brown if (flg) then 11365afa91aSSatish Balay call SNESSetConvergenceTest(snes,MySNESConverged,0,PETSC_NULL_FUNCTION,ierr) 11465afa91aSSatish Balay CHKERRA(ierr) 115c4762a1bSJed Brown endif 116c4762a1bSJed Brown 117c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 118c4762a1bSJed Brown! Create vector data structures; set function evaluation routine 119c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 120c4762a1bSJed Brown 121c4762a1bSJed Brown! Create distributed array (DMDA) to manage parallel grid and vectors 122c4762a1bSJed Brown 12342ce371bSBarry Smith! This really needs only the star-type stencil, but we use the box stencil 12460cf0239SBarry Smith 12565afa91aSSatish Balay call DMDACreate2d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,i4,i4,PETSC_DECIDE,PETSC_DECIDE, & 1265d83a8b1SBarry Smith i1,i1, PETSC_NULL_INTEGER_ARRAY,PETSC_NULL_INTEGER_ARRAY,da,ierr) 12765afa91aSSatish Balay CHKERRA(ierr) 12865afa91aSSatish Balay call DMSetFromOptions(da,ierr) 12965afa91aSSatish Balay CHKERRA(ierr) 13065afa91aSSatish Balay call DMSetUp(da,ierr) 13165afa91aSSatish Balay CHKERRA(ierr) 132c4762a1bSJed Brown 133c4762a1bSJed Brown! Extract global and local vectors from DMDA; then duplicate for remaining 134c4762a1bSJed Brown! vectors that are the same types 135c4762a1bSJed Brown 13665afa91aSSatish Balay call DMCreateGlobalVector(da,x,ierr) 13765afa91aSSatish Balay CHKERRA(ierr) 13865afa91aSSatish Balay call VecDuplicate(x,r,ierr) 13965afa91aSSatish Balay CHKERRA(ierr) 140c4762a1bSJed Brown 141c4762a1bSJed Brown! Get local grid boundaries (for 2-dimensional DMDA) 142c4762a1bSJed Brown 14360cf0239SBarry Smith call DMDAGetInfo(da,PETSC_NULL_INTEGER,mx,my,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER, & 144ce78bad3SBarry Smith PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,PETSC_NULL_DMBOUNDARYTYPE,PETSC_NULL_DMBOUNDARYTYPE, & 145ce78bad3SBarry Smith PETSC_NULL_DMBOUNDARYTYPE,PETSC_NULL_DMDASTENCILTYPE,ierr) 14665afa91aSSatish Balay CHKERRA(ierr) 14765afa91aSSatish Balay call DMDAGetCorners(da,xs,ys,PETSC_NULL_INTEGER,xm,ym,PETSC_NULL_INTEGER,ierr) 14865afa91aSSatish Balay CHKERRA(ierr) 14965afa91aSSatish Balay call DMDAGetGhostCorners(da,gxs,gys,PETSC_NULL_INTEGER,gxm,gym,PETSC_NULL_INTEGER,ierr) 15065afa91aSSatish Balay CHKERRA(ierr) 151c4762a1bSJed Brown 152c4762a1bSJed Brown! Here we shift the starting indices up by one so that we can easily 153c4762a1bSJed Brown! use the Fortran convention of 1-based indices (rather 0-based indices). 154c4762a1bSJed Brown 155c4762a1bSJed Brown xs = xs+1 156c4762a1bSJed Brown ys = ys+1 157c4762a1bSJed Brown gxs = gxs+1 158c4762a1bSJed Brown gys = gys+1 159c4762a1bSJed Brown 160c4762a1bSJed Brown ye = ys+ym-1 161c4762a1bSJed Brown xe = xs+xm-1 162c4762a1bSJed Brown gye = gys+gym-1 163c4762a1bSJed Brown gxe = gxs+gxm-1 164c4762a1bSJed Brown 165c4762a1bSJed Brown! Set function evaluation routine and vector 166c4762a1bSJed Brown 16765afa91aSSatish Balay call DMDASNESSetFunctionLocal(da,INSERT_VALUES,FormFunctionLocal,da,ierr) 16865afa91aSSatish Balay CHKERRA(ierr) 16965afa91aSSatish Balay call DMDASNESSetJacobianLocal(da,FormJacobianLocal,da,ierr) 17065afa91aSSatish Balay CHKERRA(ierr) 17165afa91aSSatish Balay call SNESSetDM(snes,da,ierr) 17265afa91aSSatish Balay CHKERRA(ierr) 173c4762a1bSJed Brown 174c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 175c4762a1bSJed Brown! Customize nonlinear solver; set runtime options 176c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 177c4762a1bSJed Brown 178c4762a1bSJed Brown! Set runtime options (e.g., -snes_monitor -snes_rtol <rtol> -ksp_type <type>) 179c4762a1bSJed Brown 18065afa91aSSatish Balay call SNESSetFromOptions(snes,ierr) 18165afa91aSSatish Balay CHKERRA(ierr) 182c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 183c4762a1bSJed Brown! Evaluate initial guess; then solve nonlinear system. 184c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 185c4762a1bSJed Brown 186c4762a1bSJed Brown! Note: The user should initialize the vector, x, with the initial guess 187c4762a1bSJed Brown! for the nonlinear solver prior to calling SNESSolve(). In particular, 188c4762a1bSJed Brown! to employ an initial guess of zero, the user should explicitly set 189c4762a1bSJed Brown! this vector to zero by calling VecSet(). 190c4762a1bSJed Brown 19165afa91aSSatish Balay call FormInitialGuess(x,ierr) 19265afa91aSSatish Balay CHKERRA(ierr) 19365afa91aSSatish Balay call SNESSolve(snes,PETSC_NULL_VEC,x,ierr) 19465afa91aSSatish Balay CHKERRA(ierr) 19565afa91aSSatish Balay call SNESGetIterationNumber(snes,its,ierr) 19665afa91aSSatish Balay CHKERRA(ierr) 197c4762a1bSJed Brown if (rank .eq. 0) then 198c4762a1bSJed Brown write(6,100) its 199c4762a1bSJed Brown endif 200c4762a1bSJed Brown 100 format('Number of SNES iterations = ',i5) 201c4762a1bSJed Brown 202c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 203c4762a1bSJed Brown! Free work space. All PETSc objects should be destroyed when they 204c4762a1bSJed Brown! are no longer needed. 205c4762a1bSJed Brown! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 206c4762a1bSJed Brown 20765afa91aSSatish Balay call VecDestroy(x,ierr) 20865afa91aSSatish Balay CHKERRA(ierr) 20965afa91aSSatish Balay call VecDestroy(r,ierr) 21065afa91aSSatish Balay CHKERRA(ierr) 21165afa91aSSatish Balay call SNESDestroy(snes,ierr) 21265afa91aSSatish Balay CHKERRA(ierr) 21365afa91aSSatish Balay call DMDestroy(da,ierr) 21465afa91aSSatish Balay CHKERRA(ierr) 21565afa91aSSatish Balay call PetscFinalize(ierr) 21665afa91aSSatish Balay CHKERRA(ierr) 217c4762a1bSJed Brown end 218c4762a1bSJed Brown 219c4762a1bSJed Brown! --------------------------------------------------------------------- 220c4762a1bSJed Brown! 221c4762a1bSJed Brown! FormInitialGuess - Forms initial approximation. 222c4762a1bSJed Brown! 223c4762a1bSJed Brown! Input Parameters: 224c4762a1bSJed Brown! X - vector 225c4762a1bSJed Brown! 226c4762a1bSJed Brown! Output Parameter: 227c4762a1bSJed Brown! X - vector 228c4762a1bSJed Brown! 229c4762a1bSJed Brown! Notes: 230c4762a1bSJed Brown! This routine serves as a wrapper for the lower-level routine 231c4762a1bSJed Brown! "ApplicationInitialGuess", where the actual computations are 232c4762a1bSJed Brown! done using the standard Fortran style of treating the local 233c4762a1bSJed Brown! vector data as a multidimensional array over the local mesh. 234c4762a1bSJed Brown! This routine merely handles ghost point scatters and accesses 235ce78bad3SBarry Smith! the local vector data via VecGetArray() and VecRestoreArray(). 236c4762a1bSJed Brown! 237c4762a1bSJed Brown subroutine FormInitialGuess(X,ierr) 238dfbbaf82SBarry Smith use ex5fmodule 239c4762a1bSJed Brown implicit none 240c4762a1bSJed Brown 241c4762a1bSJed Brown! Input/output variables: 242c4762a1bSJed Brown Vec X 243c4762a1bSJed Brown PetscErrorCode ierr 244c4762a1bSJed Brown! Declarations for use with local arrays: 24542ce371bSBarry Smith PetscScalar, pointer :: lx_v(:) 246c4762a1bSJed Brown 247c4762a1bSJed Brown ierr = 0 248c4762a1bSJed Brown 249c4762a1bSJed Brown! Get a pointer to vector data. 250c4762a1bSJed Brown! - For default PETSc vectors, VecGetArray() returns a pointer to 251c4762a1bSJed Brown! the data array. Otherwise, the routine is implementation dependent. 252c4762a1bSJed Brown! - You MUST call VecRestoreArray() when you no longer need access to 253c4762a1bSJed Brown! the array. 254c4762a1bSJed Brown! - Note that the Fortran interface to VecGetArray() differs from the 255c4762a1bSJed Brown! C version. See the users manual for details. 256c4762a1bSJed Brown 257ce78bad3SBarry Smith call VecGetArray(X,lx_v,ierr) 25865afa91aSSatish Balay CHKERRQ(ierr) 259c4762a1bSJed Brown 260c4762a1bSJed Brown! Compute initial guess over the locally owned part of the grid 261c4762a1bSJed Brown 26242ce371bSBarry Smith call InitialGuessLocal(lx_v,ierr) 26365afa91aSSatish Balay CHKERRQ(ierr) 264c4762a1bSJed Brown 265c4762a1bSJed Brown! Restore vector 266c4762a1bSJed Brown 267ce78bad3SBarry Smith call VecRestoreArray(X,lx_v,ierr) 26865afa91aSSatish Balay CHKERRQ(ierr) 269c4762a1bSJed Brown 270c4762a1bSJed Brown end 271c4762a1bSJed Brown 272c4762a1bSJed Brown! --------------------------------------------------------------------- 273c4762a1bSJed Brown! 274c4762a1bSJed Brown! InitialGuessLocal - Computes initial approximation, called by 275c4762a1bSJed Brown! the higher level routine FormInitialGuess(). 276c4762a1bSJed Brown! 277c4762a1bSJed Brown! Input Parameter: 278c4762a1bSJed Brown! x - local vector data 279c4762a1bSJed Brown! 280c4762a1bSJed Brown! Output Parameters: 281c4762a1bSJed Brown! x - local vector data 282c4762a1bSJed Brown! ierr - error code 283c4762a1bSJed Brown! 284c4762a1bSJed Brown! Notes: 285c4762a1bSJed Brown! This routine uses standard Fortran-style computations over a 2-dim array. 286c4762a1bSJed Brown! 287c4762a1bSJed Brown subroutine InitialGuessLocal(x,ierr) 288dfbbaf82SBarry Smith use ex5fmodule 289c4762a1bSJed Brown implicit none 290c4762a1bSJed Brown 291c4762a1bSJed Brown! Input/output variables: 292c4762a1bSJed Brown PetscScalar x(xs:xe,ys:ye) 293c4762a1bSJed Brown PetscErrorCode ierr 294c4762a1bSJed Brown 295c4762a1bSJed Brown! Local variables: 296c4762a1bSJed Brown PetscInt i,j 297c4762a1bSJed Brown PetscReal temp1,temp,one,hx,hy 298c4762a1bSJed Brown 299c4762a1bSJed Brown! Set parameters 300c4762a1bSJed Brown 301c4762a1bSJed Brown ierr = 0 302c4762a1bSJed Brown one = 1.0 303bb060b03SBarry Smith hx = one/((real(mx)-1)) 304bb060b03SBarry Smith hy = one/((real(my)-1)) 305c4762a1bSJed Brown temp1 = lambda/(lambda + one) 306c4762a1bSJed Brown 307c4762a1bSJed Brown do 20 j=ys,ye 308bb060b03SBarry Smith temp = (real(min(j-1,my-j)))*hy 309c4762a1bSJed Brown do 10 i=xs,xe 310c4762a1bSJed Brown if (i .eq. 1 .or. j .eq. 1 .or. i .eq. mx .or. j .eq. my) then 311c4762a1bSJed Brown x(i,j) = 0.0 312c4762a1bSJed Brown else 313bb060b03SBarry Smith x(i,j) = temp1 * sqrt(min(real(min(i-1,mx-i))*hx,(temp))) 314c4762a1bSJed Brown endif 315c4762a1bSJed Brown 10 continue 316c4762a1bSJed Brown 20 continue 317c4762a1bSJed Brown 318c4762a1bSJed Brown end 319c4762a1bSJed Brown 320c4762a1bSJed Brown! --------------------------------------------------------------------- 321c4762a1bSJed Brown! 322c4762a1bSJed Brown! FormFunctionLocal - Computes nonlinear function, called by 323c4762a1bSJed Brown! the higher level routine FormFunction(). 324c4762a1bSJed Brown! 325c4762a1bSJed Brown! Input Parameter: 326c4762a1bSJed Brown! x - local vector data 327c4762a1bSJed Brown! 328c4762a1bSJed Brown! Output Parameters: 329c4762a1bSJed Brown! f - local vector data, f(x) 330c4762a1bSJed Brown! ierr - error code 331c4762a1bSJed Brown! 332c4762a1bSJed Brown! Notes: 333c4762a1bSJed Brown! This routine uses standard Fortran-style computations over a 2-dim array. 334c4762a1bSJed Brown! 335c4762a1bSJed Brown! 336c4762a1bSJed Brown subroutine FormFunctionLocal(info,x,f,da,ierr) 337dfbbaf82SBarry Smith use ex5fmodule 338c4762a1bSJed Brown implicit none 339c4762a1bSJed Brown 340c4762a1bSJed Brown DM da 341c4762a1bSJed Brown 342c4762a1bSJed Brown! Input/output variables: 343ce78bad3SBarry Smith DMDALocalInfo info 344c4762a1bSJed Brown PetscScalar x(gxs:gxe,gys:gye) 345c4762a1bSJed Brown PetscScalar f(xs:xe,ys:ye) 346c4762a1bSJed Brown PetscErrorCode ierr 347c4762a1bSJed Brown 348c4762a1bSJed Brown! Local variables: 349c4762a1bSJed Brown PetscScalar two,one,hx,hy 350c4762a1bSJed Brown PetscScalar hxdhy,hydhx,sc 351c4762a1bSJed Brown PetscScalar u,uxx,uyy 352c4762a1bSJed Brown PetscInt i,j 353c4762a1bSJed Brown 354ce78bad3SBarry Smith xs = info%XS+1 355ce78bad3SBarry Smith xe = xs+info%XM-1 356ce78bad3SBarry Smith ys = info%YS+1 357ce78bad3SBarry Smith ye = ys+info%YM-1 358ce78bad3SBarry Smith mx = info%MX 359ce78bad3SBarry Smith my = info%MY 360c4762a1bSJed Brown 361c4762a1bSJed Brown one = 1.0 362c4762a1bSJed Brown two = 2.0 363bb060b03SBarry Smith hx = one/(real(mx)-1) 364bb060b03SBarry Smith hy = one/(real(my)-1) 365c4762a1bSJed Brown sc = hx*hy*lambda 366c4762a1bSJed Brown hxdhy = hx/hy 367c4762a1bSJed Brown hydhx = hy/hx 368c4762a1bSJed Brown 369c4762a1bSJed Brown! Compute function over the locally owned part of the grid 370c4762a1bSJed Brown 371c4762a1bSJed Brown do 20 j=ys,ye 372c4762a1bSJed Brown do 10 i=xs,xe 373c4762a1bSJed Brown if (i .eq. 1 .or. j .eq. 1 .or. i .eq. mx .or. j .eq. my) then 374c4762a1bSJed Brown f(i,j) = x(i,j) 375c4762a1bSJed Brown else 376c4762a1bSJed Brown u = x(i,j) 377c4762a1bSJed Brown uxx = hydhx * (two*u - x(i-1,j) - x(i+1,j)) 378c4762a1bSJed Brown uyy = hxdhy * (two*u - x(i,j-1) - x(i,j+1)) 379c4762a1bSJed Brown f(i,j) = uxx + uyy - sc*exp(u) 380c4762a1bSJed Brown endif 381c4762a1bSJed Brown 10 continue 382c4762a1bSJed Brown 20 continue 383c4762a1bSJed Brown 38465afa91aSSatish Balay call PetscLogFlops(11.0d0*ym*xm,ierr) 38565afa91aSSatish Balay CHKERRQ(ierr) 386c4762a1bSJed Brown 387c4762a1bSJed Brown end 388c4762a1bSJed Brown 389c4762a1bSJed Brown! --------------------------------------------------------------------- 390c4762a1bSJed Brown! 391c4762a1bSJed Brown! FormJacobianLocal - Computes Jacobian matrix, called by 392c4762a1bSJed Brown! the higher level routine FormJacobian(). 393c4762a1bSJed Brown! 394c4762a1bSJed Brown! Input Parameters: 395c4762a1bSJed Brown! x - local vector data 396c4762a1bSJed Brown! 397c4762a1bSJed Brown! Output Parameters: 398c4762a1bSJed Brown! jac - Jacobian matrix 3997addb90fSBarry Smith! jac_prec - optionally different matrix used to construct the preconditioner (not used here) 400c4762a1bSJed Brown! ierr - error code 401c4762a1bSJed Brown! 402c4762a1bSJed Brown! Notes: 403c4762a1bSJed Brown! This routine uses standard Fortran-style computations over a 2-dim array. 404c4762a1bSJed Brown! 405c4762a1bSJed Brown! Notes: 406c4762a1bSJed Brown! Due to grid point reordering with DMDAs, we must always work 407c4762a1bSJed Brown! with the local grid points, and then transform them to the new 408c4762a1bSJed Brown! global numbering with the "ltog" mapping 409c4762a1bSJed Brown! We cannot work directly with the global numbers for the original 410c4762a1bSJed Brown! uniprocessor grid! 411c4762a1bSJed Brown! 412c4762a1bSJed Brown! Two methods are available for imposing this transformation 413c4762a1bSJed Brown! when setting matrix entries: 414c4762a1bSJed Brown! (A) MatSetValuesLocal(), using the local ordering (including 415c4762a1bSJed Brown! ghost points!) 416c4762a1bSJed Brown! by calling MatSetValuesLocal() 417c4762a1bSJed Brown! (B) MatSetValues(), using the global ordering 418c4762a1bSJed Brown! - Use DMDAGetGlobalIndices() to extract the local-to-global map 419c4762a1bSJed Brown! - Then apply this map explicitly yourself 420c4762a1bSJed Brown! - Set matrix entries using the global ordering by calling 421c4762a1bSJed Brown! MatSetValues() 422c4762a1bSJed Brown! Option (A) seems cleaner/easier in many cases, and is the procedure 423c4762a1bSJed Brown! used in this example. 424c4762a1bSJed Brown! 425c4762a1bSJed Brown subroutine FormJacobianLocal(info,x,A,jac,da,ierr) 426dfbbaf82SBarry Smith use ex5fmodule 427c4762a1bSJed Brown implicit none 428c4762a1bSJed Brown 429c4762a1bSJed Brown DM da 430c4762a1bSJed Brown 431c4762a1bSJed Brown! Input/output variables: 432c4762a1bSJed Brown PetscScalar x(gxs:gxe,gys:gye) 433c4762a1bSJed Brown Mat A,jac 434c4762a1bSJed Brown PetscErrorCode ierr 435ce78bad3SBarry Smith DMDALocalInfo info 436c4762a1bSJed Brown 437c4762a1bSJed Brown! Local variables: 438c4762a1bSJed Brown PetscInt row,col(5),i,j,i1,i5 439c4762a1bSJed Brown PetscScalar two,one,hx,hy,v(5) 440c4762a1bSJed Brown PetscScalar hxdhy,hydhx,sc 441c4762a1bSJed Brown 442c4762a1bSJed Brown! Set parameters 443c4762a1bSJed Brown 444c4762a1bSJed Brown i1 = 1 445c4762a1bSJed Brown i5 = 5 446c4762a1bSJed Brown one = 1.0 447c4762a1bSJed Brown two = 2.0 448bb060b03SBarry Smith hx = one/(real(mx)-1) 449bb060b03SBarry Smith hy = one/(real(my)-1) 450c4762a1bSJed Brown sc = hx*hy 451c4762a1bSJed Brown hxdhy = hx/hy 452c4762a1bSJed Brown hydhx = hy/hx 453e0b71005SStefano Zampini! -Wmaybe-uninitialized 454e0b71005SStefano Zampini v = 0.0 455e0b71005SStefano Zampini col = 0 456c4762a1bSJed Brown 457c4762a1bSJed Brown! Compute entries for the locally owned part of the Jacobian. 458c4762a1bSJed Brown! - Currently, all PETSc parallel matrix formats are partitioned by 459c4762a1bSJed Brown! contiguous chunks of rows across the processors. 460c4762a1bSJed Brown! - Each processor needs to insert only elements that it owns 461c4762a1bSJed Brown! locally (but any non-local elements will be sent to the 462c4762a1bSJed Brown! appropriate processor during matrix assembly). 463c4762a1bSJed Brown! - Here, we set all entries for a particular row at once. 464c4762a1bSJed Brown! - We can set matrix entries either using either 465c4762a1bSJed Brown! MatSetValuesLocal() or MatSetValues(), as discussed above. 466c4762a1bSJed Brown! - Note that MatSetValues() uses 0-based row and column numbers 467c4762a1bSJed Brown! in Fortran as well as in C. 468c4762a1bSJed Brown 469c4762a1bSJed Brown do 20 j=ys,ye 470c4762a1bSJed Brown row = (j - gys)*gxm + xs - gxs - 1 471c4762a1bSJed Brown do 10 i=xs,xe 472c4762a1bSJed Brown row = row + 1 473c4762a1bSJed Brown! boundary points 474c4762a1bSJed Brown if (i .eq. 1 .or. j .eq. 1 .or. i .eq. mx .or. j .eq. my) then 475c4762a1bSJed Brown! Some f90 compilers need 4th arg to be of same type in both calls 476c4762a1bSJed Brown col(1) = row 477c4762a1bSJed Brown v(1) = one 4785d83a8b1SBarry Smith call MatSetValuesLocal(jac,i1,[row],i1,[col],[v],INSERT_VALUES,ierr) 47965afa91aSSatish Balay CHKERRQ(ierr) 480c4762a1bSJed Brown! interior grid points 481c4762a1bSJed Brown else 482c4762a1bSJed Brown v(1) = -hxdhy 483c4762a1bSJed Brown v(2) = -hydhx 484c4762a1bSJed Brown v(3) = two*(hydhx + hxdhy) - sc*lambda*exp(x(i,j)) 485c4762a1bSJed Brown v(4) = -hydhx 486c4762a1bSJed Brown v(5) = -hxdhy 487c4762a1bSJed Brown col(1) = row - gxm 488c4762a1bSJed Brown col(2) = row - 1 489c4762a1bSJed Brown col(3) = row 490c4762a1bSJed Brown col(4) = row + 1 491c4762a1bSJed Brown col(5) = row + gxm 4925d83a8b1SBarry Smith call MatSetValuesLocal(jac,i1,[row],i5,[col],[v], INSERT_VALUES,ierr) 49365afa91aSSatish Balay CHKERRQ(ierr) 494c4762a1bSJed Brown endif 495c4762a1bSJed Brown 10 continue 496c4762a1bSJed Brown 20 continue 49765afa91aSSatish Balay call MatAssemblyBegin(jac,MAT_FINAL_ASSEMBLY,ierr) 49865afa91aSSatish Balay CHKERRQ(ierr) 49965afa91aSSatish Balay call MatAssemblyEnd(jac,MAT_FINAL_ASSEMBLY,ierr) 50065afa91aSSatish Balay CHKERRQ(ierr) 501c4762a1bSJed Brown if (A .ne. jac) then 50265afa91aSSatish Balay call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY,ierr) 50365afa91aSSatish Balay CHKERRQ(ierr) 50465afa91aSSatish Balay call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY,ierr) 50565afa91aSSatish Balay CHKERRQ(ierr) 506c4762a1bSJed Brown endif 507c4762a1bSJed Brown end 508c4762a1bSJed Brown 509c4762a1bSJed Brown! 510c4762a1bSJed Brown! Simple convergence test based on the infinity norm of the residual being small 511c4762a1bSJed Brown! 512c4762a1bSJed Brown subroutine MySNESConverged(snes,it,xnorm,snorm,fnorm,reason,dummy,ierr) 513dfbbaf82SBarry Smith use ex5fmodule 514c4762a1bSJed Brown implicit none 515c4762a1bSJed Brown 516c4762a1bSJed Brown SNES snes 517c4762a1bSJed Brown PetscInt it,dummy 518c4762a1bSJed Brown PetscReal xnorm,snorm,fnorm,nrm 519c4762a1bSJed Brown SNESConvergedReason reason 520c4762a1bSJed Brown Vec f 521c4762a1bSJed Brown PetscErrorCode ierr 522c4762a1bSJed Brown 52365afa91aSSatish Balay call SNESGetFunction(snes,f,PETSC_NULL_FUNCTION,dummy,ierr) 52465afa91aSSatish Balay CHKERRQ(ierr) 52565afa91aSSatish Balay call VecNorm(f,NORM_INFINITY,nrm,ierr) 52665afa91aSSatish Balay CHKERRQ(ierr) 527c4762a1bSJed Brown if (nrm .le. 1.e-5) reason = SNES_CONVERGED_FNORM_ABS 528c4762a1bSJed Brown 529c4762a1bSJed Brown end 530c4762a1bSJed Brown 531c4762a1bSJed Brown!/*TEST 532c4762a1bSJed Brown! 533c4762a1bSJed Brown! build: 534c4762a1bSJed Brown! requires: !complex !single 535c4762a1bSJed Brown! 536c4762a1bSJed Brown! test: 537c4762a1bSJed Brown! nsize: 4 5388f8b3c79SStefano Zampini! args: -snes_mf -pc_type none -da_processors_x 4 -da_processors_y 1 -snes_monitor_short \ 5398f8b3c79SStefano Zampini! -ksp_gmres_cgs_refinement_type refine_always 540c4762a1bSJed Brown! 541c4762a1bSJed Brown! test: 542c4762a1bSJed Brown! suffix: 2 543c4762a1bSJed Brown! nsize: 4 544c4762a1bSJed Brown! args: -da_processors_x 2 -da_processors_y 2 -snes_monitor_short -ksp_gmres_cgs_refinement_type refine_always 545c4762a1bSJed Brown! 546c4762a1bSJed Brown! test: 547c4762a1bSJed Brown! suffix: 3 548c4762a1bSJed Brown! nsize: 3 549c4762a1bSJed Brown! args: -snes_fd -snes_monitor_short -ksp_gmres_cgs_refinement_type refine_always 550c4762a1bSJed Brown! 551c4762a1bSJed Brown! test: 552c4762a1bSJed Brown! suffix: 6 553c4762a1bSJed Brown! nsize: 1 554c4762a1bSJed Brown! args: -snes_monitor_short -my_snes_convergence 555c4762a1bSJed Brown! 556c4762a1bSJed Brown!TEST*/ 557