xref: /petsc/src/tao/unconstrained/tutorials/minsurf1.c (revision 327415f76d85372a4417cf1aaa14db707d4d6c04)
1c4762a1bSJed Brown /* Program usage: mpiexec -n 1 minsurf1 [-help] [all TAO options] */
2c4762a1bSJed Brown 
3c4762a1bSJed Brown /*  Include "petsctao.h" so we can use TAO solvers.  */
4c4762a1bSJed Brown #include <petsctao.h>
5c4762a1bSJed Brown 
6c4762a1bSJed Brown static char  help[] =
7c4762a1bSJed Brown "This example demonstrates use of the TAO package to \n\
8c4762a1bSJed Brown solve an unconstrained minimization problem.  This example is based on a \n\
9c4762a1bSJed Brown problem from the MINPACK-2 test suite.  Given a rectangular 2-D domain and \n\
10c4762a1bSJed Brown boundary values along the edges of the domain, the objective is to find the\n\
11c4762a1bSJed Brown surface with the minimal area that satisfies the boundary conditions.\n\
12c4762a1bSJed Brown The command line options are:\n\
13c4762a1bSJed Brown   -mx <xg>, where <xg> = number of grid points in the 1st coordinate direction\n\
14c4762a1bSJed Brown   -my <yg>, where <yg> = number of grid points in the 2nd coordinate direction\n\
15c4762a1bSJed Brown   -start <st>, where <st> =0 for zero vector, and an average of the boundary conditions otherwise \n\n";
16c4762a1bSJed Brown 
17c4762a1bSJed Brown /*
18c4762a1bSJed Brown    User-defined application context - contains data needed by the
19c4762a1bSJed Brown    application-provided call-back routines, FormFunctionGradient()
20c4762a1bSJed Brown    and FormHessian().
21c4762a1bSJed Brown */
22c4762a1bSJed Brown typedef struct {
23c4762a1bSJed Brown   PetscInt    mx, my;                 /* discretization in x, y directions */
24c4762a1bSJed Brown   PetscReal   *bottom, *top, *left, *right;             /* boundary values */
25c4762a1bSJed Brown   Mat         H;
26c4762a1bSJed Brown } AppCtx;
27c4762a1bSJed Brown 
28c4762a1bSJed Brown /* -------- User-defined Routines --------- */
29c4762a1bSJed Brown 
30c4762a1bSJed Brown static PetscErrorCode MSA_BoundaryConditions(AppCtx*);
31c4762a1bSJed Brown static PetscErrorCode MSA_InitialPoint(AppCtx*,Vec);
32c4762a1bSJed Brown static PetscErrorCode QuadraticH(AppCtx*,Vec,Mat);
33c4762a1bSJed Brown PetscErrorCode FormFunctionGradient(Tao,Vec,PetscReal*,Vec,void*);
34c4762a1bSJed Brown PetscErrorCode FormHessian(Tao,Vec,Mat,Mat,void*);
35c4762a1bSJed Brown 
36c4762a1bSJed Brown int main(int argc, char **argv)
37c4762a1bSJed Brown {
38c4762a1bSJed Brown   PetscInt           N;                 /* Size of vector */
39c4762a1bSJed Brown   PetscMPIInt        size;              /* Number of processors */
40c4762a1bSJed Brown   Vec                x;                 /* solution, gradient vectors */
41c4762a1bSJed Brown   KSP                ksp;               /*  PETSc Krylov subspace method */
42c4762a1bSJed Brown   PetscBool          flg;               /* A return value when checking for user options */
43c4762a1bSJed Brown   Tao                tao;               /* Tao solver context */
44c4762a1bSJed Brown   AppCtx             user;              /* user-defined work context */
45c4762a1bSJed Brown 
46c4762a1bSJed Brown   /* Initialize TAO,PETSc */
47*327415f7SBarry Smith   PetscFunctionBeginUser;
489566063dSJacob Faibussowitsch   PetscCall(PetscInitialize(&argc, &argv,(char *)0,help));
49c4762a1bSJed Brown 
509566063dSJacob Faibussowitsch   PetscCallMPI(MPI_Comm_size(MPI_COMM_WORLD,&size));
513c859ba3SBarry Smith   PetscCheck(size == 1,PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Incorrect number of processors");
52c4762a1bSJed Brown 
53c4762a1bSJed Brown   /* Specify default dimension of the problem */
54c4762a1bSJed Brown   user.mx = 4; user.my = 4;
55c4762a1bSJed Brown 
56c4762a1bSJed Brown   /* Check for any command line arguments that override defaults */
579566063dSJacob Faibussowitsch   PetscCall(PetscOptionsGetInt(NULL,NULL,"-mx",&user.mx,&flg));
589566063dSJacob Faibussowitsch   PetscCall(PetscOptionsGetInt(NULL,NULL,"-my",&user.my,&flg));
59c4762a1bSJed Brown 
609566063dSJacob Faibussowitsch   PetscCall(PetscPrintf(PETSC_COMM_SELF,"\n---- Minimum Surface Area Problem -----\n"));
6163a3b9bcSJacob Faibussowitsch   PetscCall(PetscPrintf(PETSC_COMM_SELF,"mx: %" PetscInt_FMT "     my: %" PetscInt_FMT "   \n\n",user.mx,user.my));
62c4762a1bSJed Brown 
63c4762a1bSJed Brown   /* Calculate any derived values from parameters */
64c4762a1bSJed Brown   N    = user.mx*user.my;
65c4762a1bSJed Brown 
66c4762a1bSJed Brown   /* Create TAO solver and set desired solution method  */
679566063dSJacob Faibussowitsch   PetscCall(TaoCreate(PETSC_COMM_SELF,&tao));
689566063dSJacob Faibussowitsch   PetscCall(TaoSetType(tao,TAOLMVM));
69c4762a1bSJed Brown 
70c4762a1bSJed Brown   /* Initialize minsurf application data structure for use in the function evaluations  */
719566063dSJacob Faibussowitsch   PetscCall(MSA_BoundaryConditions(&user));            /* Application specific routine */
72c4762a1bSJed Brown 
73c4762a1bSJed Brown   /*
74c4762a1bSJed Brown      Create a vector to hold the variables.  Compute an initial solution.
75c4762a1bSJed Brown      Set this vector, which will be used by TAO.
76c4762a1bSJed Brown   */
779566063dSJacob Faibussowitsch   PetscCall(VecCreateSeq(PETSC_COMM_SELF,N,&x));
789566063dSJacob Faibussowitsch   PetscCall(MSA_InitialPoint(&user,x));                /* Application specific routine */
799566063dSJacob Faibussowitsch   PetscCall(TaoSetSolution(tao,x));   /* A TAO routine                */
80c4762a1bSJed Brown 
81c4762a1bSJed Brown   /* Provide TAO routines for function, gradient, and Hessian evaluation */
829566063dSJacob Faibussowitsch   PetscCall(TaoSetObjectiveAndGradient(tao,NULL,FormFunctionGradient,(void *)&user));
83c4762a1bSJed Brown 
84c4762a1bSJed Brown   /* Create a matrix data structure to store the Hessian.  This structure will be used by TAO */
859566063dSJacob Faibussowitsch   PetscCall(MatCreateSeqAIJ(PETSC_COMM_SELF,N,N,7,NULL,&(user.H)));
869566063dSJacob Faibussowitsch   PetscCall(MatSetOption(user.H,MAT_SYMMETRIC,PETSC_TRUE));
879566063dSJacob Faibussowitsch   PetscCall(TaoSetHessian(tao,user.H,user.H,FormHessian,(void *)&user));
88c4762a1bSJed Brown 
89c4762a1bSJed Brown   /* Check for any TAO command line options */
909566063dSJacob Faibussowitsch   PetscCall(TaoSetFromOptions(tao));
91c4762a1bSJed Brown 
92c4762a1bSJed Brown   /* Limit the number of iterations in the KSP linear solver */
939566063dSJacob Faibussowitsch   PetscCall(TaoGetKSP(tao,&ksp));
941baa6e33SBarry Smith   if (ksp) PetscCall(KSPSetTolerances(ksp,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT,user.mx*user.my));
95c4762a1bSJed Brown 
96c4762a1bSJed Brown   /* SOLVE THE APPLICATION */
979566063dSJacob Faibussowitsch   PetscCall(TaoSolve(tao));
98c4762a1bSJed Brown 
999566063dSJacob Faibussowitsch   PetscCall(TaoDestroy(&tao));
1009566063dSJacob Faibussowitsch   PetscCall(VecDestroy(&x));
1019566063dSJacob Faibussowitsch   PetscCall(MatDestroy(&user.H));
1029566063dSJacob Faibussowitsch   PetscCall(PetscFree(user.bottom));
1039566063dSJacob Faibussowitsch   PetscCall(PetscFree(user.top));
1049566063dSJacob Faibussowitsch   PetscCall(PetscFree(user.left));
1059566063dSJacob Faibussowitsch   PetscCall(PetscFree(user.right));
106c4762a1bSJed Brown 
1079566063dSJacob Faibussowitsch   PetscCall(PetscFinalize());
108b122ec5aSJacob Faibussowitsch   return 0;
109c4762a1bSJed Brown }
110c4762a1bSJed Brown 
111c4762a1bSJed Brown /* -------------------------------------------------------------------- */
112c4762a1bSJed Brown 
113c4762a1bSJed Brown /*  FormFunctionGradient - Evaluates function and corresponding gradient.
114c4762a1bSJed Brown 
115c4762a1bSJed Brown     Input Parameters:
116c4762a1bSJed Brown .   tao     - the Tao context
117c4762a1bSJed Brown .   X       - input vector
118c4762a1bSJed Brown .   userCtx - optional user-defined context, as set by TaoSetFunctionGradient()
119c4762a1bSJed Brown 
120c4762a1bSJed Brown     Output Parameters:
121c4762a1bSJed Brown .   fcn     - the newly evaluated function
122c4762a1bSJed Brown .   G       - vector containing the newly evaluated gradient
123c4762a1bSJed Brown */
124c4762a1bSJed Brown PetscErrorCode FormFunctionGradient(Tao tao,Vec X,PetscReal *fcn,Vec G,void *userCtx)
125c4762a1bSJed Brown {
126c4762a1bSJed Brown   AppCtx            *user = (AppCtx *) userCtx;
127c4762a1bSJed Brown   PetscInt          i,j,row;
128c4762a1bSJed Brown   PetscInt          mx=user->mx, my=user->my;
129c4762a1bSJed Brown   PetscReal         rhx=mx+1, rhy=my+1;
130c4762a1bSJed Brown   PetscReal         hx=1.0/(mx+1),hy=1.0/(my+1), hydhx=hy/hx, hxdhy=hx/hy, area=0.5*hx*hy, ft=0;
131c4762a1bSJed Brown   PetscReal         f1,f2,f3,f4,f5,f6,d1,d2,d3,d4,d5,d6,d7,d8,xc,xl,xr,xt,xb,xlt,xrb;
132c4762a1bSJed Brown   PetscReal         df1dxc,df2dxc,df3dxc,df4dxc,df5dxc,df6dxc;
133c4762a1bSJed Brown   PetscReal         zero=0.0;
134c4762a1bSJed Brown   PetscScalar       *g;
135c4762a1bSJed Brown   const PetscScalar *x;
136c4762a1bSJed Brown 
137c4762a1bSJed Brown   PetscFunctionBeginUser;
1389566063dSJacob Faibussowitsch   PetscCall(VecSet(G, zero));
139c4762a1bSJed Brown 
1409566063dSJacob Faibussowitsch   PetscCall(VecGetArrayRead(X,&x));
1419566063dSJacob Faibussowitsch   PetscCall(VecGetArray(G,&g));
142c4762a1bSJed Brown 
143c4762a1bSJed Brown   /* Compute function over the locally owned part of the mesh */
144c4762a1bSJed Brown   for (j=0; j<my; j++) {
145c4762a1bSJed Brown     for (i=0; i< mx; i++) {
146c4762a1bSJed Brown       row=(j)*mx + (i);
147c4762a1bSJed Brown       xc = x[row];
148c4762a1bSJed Brown       xlt=xrb=xl=xr=xb=xt=xc;
149c4762a1bSJed Brown       if (i==0) { /* left side */
150c4762a1bSJed Brown         xl  = user->left[j+1];
151c4762a1bSJed Brown         xlt = user->left[j+2];
152c4762a1bSJed Brown       } else {
153c4762a1bSJed Brown         xl = x[row-1];
154c4762a1bSJed Brown       }
155c4762a1bSJed Brown 
156c4762a1bSJed Brown       if (j==0) { /* bottom side */
157c4762a1bSJed Brown         xb  = user->bottom[i+1];
158c4762a1bSJed Brown         xrb = user->bottom[i+2];
159c4762a1bSJed Brown       } else {
160c4762a1bSJed Brown         xb = x[row-mx];
161c4762a1bSJed Brown       }
162c4762a1bSJed Brown 
163c4762a1bSJed Brown       if (i+1 == mx) { /* right side */
164c4762a1bSJed Brown         xr  = user->right[j+1];
165c4762a1bSJed Brown         xrb = user->right[j];
166c4762a1bSJed Brown       } else {
167c4762a1bSJed Brown         xr = x[row+1];
168c4762a1bSJed Brown       }
169c4762a1bSJed Brown 
170c4762a1bSJed Brown       if (j+1==0+my) { /* top side */
171c4762a1bSJed Brown         xt  = user->top[i+1];
172c4762a1bSJed Brown         xlt = user->top[i];
173c4762a1bSJed Brown       }else {
174c4762a1bSJed Brown         xt = x[row+mx];
175c4762a1bSJed Brown       }
176c4762a1bSJed Brown 
177c4762a1bSJed Brown       if (i>0 && j+1<my) {
178c4762a1bSJed Brown         xlt = x[row-1+mx];
179c4762a1bSJed Brown       }
180c4762a1bSJed Brown       if (j>0 && i+1<mx) {
181c4762a1bSJed Brown         xrb = x[row+1-mx];
182c4762a1bSJed Brown       }
183c4762a1bSJed Brown 
184c4762a1bSJed Brown       d1 = (xc-xl);
185c4762a1bSJed Brown       d2 = (xc-xr);
186c4762a1bSJed Brown       d3 = (xc-xt);
187c4762a1bSJed Brown       d4 = (xc-xb);
188c4762a1bSJed Brown       d5 = (xr-xrb);
189c4762a1bSJed Brown       d6 = (xrb-xb);
190c4762a1bSJed Brown       d7 = (xlt-xl);
191c4762a1bSJed Brown       d8 = (xt-xlt);
192c4762a1bSJed Brown 
193c4762a1bSJed Brown       df1dxc = d1*hydhx;
194c4762a1bSJed Brown       df2dxc = (d1*hydhx + d4*hxdhy);
195c4762a1bSJed Brown       df3dxc = d3*hxdhy;
196c4762a1bSJed Brown       df4dxc = (d2*hydhx + d3*hxdhy);
197c4762a1bSJed Brown       df5dxc = d2*hydhx;
198c4762a1bSJed Brown       df6dxc = d4*hxdhy;
199c4762a1bSJed Brown 
200c4762a1bSJed Brown       d1 *= rhx;
201c4762a1bSJed Brown       d2 *= rhx;
202c4762a1bSJed Brown       d3 *= rhy;
203c4762a1bSJed Brown       d4 *= rhy;
204c4762a1bSJed Brown       d5 *= rhy;
205c4762a1bSJed Brown       d6 *= rhx;
206c4762a1bSJed Brown       d7 *= rhy;
207c4762a1bSJed Brown       d8 *= rhx;
208c4762a1bSJed Brown 
209c4762a1bSJed Brown       f1 = PetscSqrtScalar(1.0 + d1*d1 + d7*d7);
210c4762a1bSJed Brown       f2 = PetscSqrtScalar(1.0 + d1*d1 + d4*d4);
211c4762a1bSJed Brown       f3 = PetscSqrtScalar(1.0 + d3*d3 + d8*d8);
212c4762a1bSJed Brown       f4 = PetscSqrtScalar(1.0 + d3*d3 + d2*d2);
213c4762a1bSJed Brown       f5 = PetscSqrtScalar(1.0 + d2*d2 + d5*d5);
214c4762a1bSJed Brown       f6 = PetscSqrtScalar(1.0 + d4*d4 + d6*d6);
215c4762a1bSJed Brown 
216c4762a1bSJed Brown       ft = ft + (f2 + f4);
217c4762a1bSJed Brown 
218c4762a1bSJed Brown       df1dxc /= f1;
219c4762a1bSJed Brown       df2dxc /= f2;
220c4762a1bSJed Brown       df3dxc /= f3;
221c4762a1bSJed Brown       df4dxc /= f4;
222c4762a1bSJed Brown       df5dxc /= f5;
223c4762a1bSJed Brown       df6dxc /= f6;
224c4762a1bSJed Brown 
225c4762a1bSJed Brown       g[row] = (df1dxc+df2dxc+df3dxc+df4dxc+df5dxc+df6dxc)/2.0;
226c4762a1bSJed Brown     }
227c4762a1bSJed Brown   }
228c4762a1bSJed Brown 
229c4762a1bSJed Brown   for (j=0; j<my; j++) {   /* left side */
230c4762a1bSJed Brown     d3 = (user->left[j+1] - user->left[j+2])*rhy;
231c4762a1bSJed Brown     d2 = (user->left[j+1] - x[j*mx])*rhx;
232c4762a1bSJed Brown     ft = ft+PetscSqrtScalar(1.0 + d3*d3 + d2*d2);
233c4762a1bSJed Brown   }
234c4762a1bSJed Brown 
235c4762a1bSJed Brown   for (i=0; i<mx; i++) { /* bottom */
236c4762a1bSJed Brown     d2 = (user->bottom[i+1]-user->bottom[i+2])*rhx;
237c4762a1bSJed Brown     d3 = (user->bottom[i+1]-x[i])*rhy;
238c4762a1bSJed Brown     ft = ft+PetscSqrtScalar(1.0 + d3*d3 + d2*d2);
239c4762a1bSJed Brown   }
240c4762a1bSJed Brown 
241c4762a1bSJed Brown   for (j=0; j< my; j++) { /* right side */
242c4762a1bSJed Brown     d1 = (x[(j+1)*mx-1]-user->right[j+1])*rhx;
243c4762a1bSJed Brown     d4 = (user->right[j]-user->right[j+1])*rhy;
244c4762a1bSJed Brown     ft = ft+PetscSqrtScalar(1.0 + d1*d1 + d4*d4);
245c4762a1bSJed Brown   }
246c4762a1bSJed Brown 
247c4762a1bSJed Brown   for (i=0; i<mx; i++) { /* top side */
248c4762a1bSJed Brown     d1 = (x[(my-1)*mx + i] - user->top[i+1])*rhy;
249c4762a1bSJed Brown     d4 = (user->top[i+1] - user->top[i])*rhx;
250c4762a1bSJed Brown     ft = ft+PetscSqrtScalar(1.0 + d1*d1 + d4*d4);
251c4762a1bSJed Brown   }
252c4762a1bSJed Brown 
253c4762a1bSJed Brown   /* Bottom left corner */
254c4762a1bSJed Brown   d1  = (user->left[0]-user->left[1])*rhy;
255c4762a1bSJed Brown   d2  = (user->bottom[0]-user->bottom[1])*rhx;
256c4762a1bSJed Brown   ft += PetscSqrtScalar(1.0 + d1*d1 + d2*d2);
257c4762a1bSJed Brown 
258c4762a1bSJed Brown   /* Top right corner */
259c4762a1bSJed Brown   d1  = (user->right[my+1] - user->right[my])*rhy;
260c4762a1bSJed Brown   d2  = (user->top[mx+1] - user->top[mx])*rhx;
261c4762a1bSJed Brown   ft += PetscSqrtScalar(1.0 + d1*d1 + d2*d2);
262c4762a1bSJed Brown 
263c4762a1bSJed Brown   (*fcn)=ft*area;
264c4762a1bSJed Brown 
265c4762a1bSJed Brown   /* Restore vectors */
2669566063dSJacob Faibussowitsch   PetscCall(VecRestoreArrayRead(X,&x));
2679566063dSJacob Faibussowitsch   PetscCall(VecRestoreArray(G,&g));
2689566063dSJacob Faibussowitsch   PetscCall(PetscLogFlops(67.0*mx*my));
269c4762a1bSJed Brown   PetscFunctionReturn(0);
270c4762a1bSJed Brown }
271c4762a1bSJed Brown 
272c4762a1bSJed Brown /* ------------------------------------------------------------------- */
273c4762a1bSJed Brown /*
274c4762a1bSJed Brown    FormHessian - Evaluates the Hessian matrix.
275c4762a1bSJed Brown 
276c4762a1bSJed Brown    Input Parameters:
277c4762a1bSJed Brown .  tao  - the Tao context
278c4762a1bSJed Brown .  x    - input vector
279c4762a1bSJed Brown .  ptr  - optional user-defined context, as set by TaoSetHessian()
280c4762a1bSJed Brown 
281c4762a1bSJed Brown    Output Parameters:
282c4762a1bSJed Brown .  H    - Hessian matrix
283c4762a1bSJed Brown .  Hpre - optionally different preconditioning matrix
284c4762a1bSJed Brown .  flg  - flag indicating matrix structure
285c4762a1bSJed Brown 
286c4762a1bSJed Brown */
287c4762a1bSJed Brown PetscErrorCode FormHessian(Tao tao,Vec X,Mat H, Mat Hpre, void *ptr)
288c4762a1bSJed Brown {
289c4762a1bSJed Brown   AppCtx         *user = (AppCtx *) ptr;
290c4762a1bSJed Brown 
291c4762a1bSJed Brown   PetscFunctionBeginUser;
292c4762a1bSJed Brown   /* Evaluate the Hessian entries*/
2939566063dSJacob Faibussowitsch   PetscCall(QuadraticH(user,X,H));
294c4762a1bSJed Brown   PetscFunctionReturn(0);
295c4762a1bSJed Brown }
296c4762a1bSJed Brown 
297c4762a1bSJed Brown /* ------------------------------------------------------------------- */
298c4762a1bSJed Brown /*
299c4762a1bSJed Brown    QuadraticH - Evaluates the Hessian matrix.
300c4762a1bSJed Brown 
301c4762a1bSJed Brown    Input Parameters:
302c4762a1bSJed Brown .  user - user-defined context, as set by TaoSetHessian()
303c4762a1bSJed Brown .  X    - input vector
304c4762a1bSJed Brown 
305c4762a1bSJed Brown    Output Parameter:
306c4762a1bSJed Brown .  H    - Hessian matrix
307c4762a1bSJed Brown */
308c4762a1bSJed Brown PetscErrorCode QuadraticH(AppCtx *user, Vec X, Mat Hessian)
309c4762a1bSJed Brown {
310c4762a1bSJed Brown   PetscInt          i,j,k,row;
311c4762a1bSJed Brown   PetscInt          mx=user->mx, my=user->my;
312c4762a1bSJed Brown   PetscInt          col[7];
313c4762a1bSJed Brown   PetscReal         hx=1.0/(mx+1), hy=1.0/(my+1), hydhx=hy/hx, hxdhy=hx/hy;
314c4762a1bSJed Brown   PetscReal         rhx=mx+1, rhy=my+1;
315c4762a1bSJed Brown   PetscReal         f1,f2,f3,f4,f5,f6,d1,d2,d3,d4,d5,d6,d7,d8,xc,xl,xr,xt,xb,xlt,xrb;
316c4762a1bSJed Brown   PetscReal         hl,hr,ht,hb,hc,htl,hbr;
317c4762a1bSJed Brown   const PetscScalar *x;
318c4762a1bSJed Brown   PetscReal         v[7];
319c4762a1bSJed Brown 
320362febeeSStefano Zampini   PetscFunctionBeginUser;
321c4762a1bSJed Brown   /* Get pointers to vector data */
3229566063dSJacob Faibussowitsch   PetscCall(VecGetArrayRead(X,&x));
323c4762a1bSJed Brown 
324c4762a1bSJed Brown   /* Initialize matrix entries to zero */
3259566063dSJacob Faibussowitsch   PetscCall(MatZeroEntries(Hessian));
326c4762a1bSJed Brown 
327c4762a1bSJed Brown   /* Set various matrix options */
3289566063dSJacob Faibussowitsch   PetscCall(MatSetOption(Hessian,MAT_IGNORE_OFF_PROC_ENTRIES,PETSC_TRUE));
329c4762a1bSJed Brown 
330c4762a1bSJed Brown   /* Compute Hessian over the locally owned part of the mesh */
331c4762a1bSJed Brown   for (i=0; i< mx; i++) {
332c4762a1bSJed Brown     for (j=0; j<my; j++) {
333c4762a1bSJed Brown 
334c4762a1bSJed Brown       row=(j)*mx + (i);
335c4762a1bSJed Brown 
336c4762a1bSJed Brown       xc = x[row];
337c4762a1bSJed Brown       xlt=xrb=xl=xr=xb=xt=xc;
338c4762a1bSJed Brown 
339c4762a1bSJed Brown       /* Left side */
340c4762a1bSJed Brown       if (i==0) {
341c4762a1bSJed Brown         xl= user->left[j+1];
342c4762a1bSJed Brown         xlt = user->left[j+2];
343c4762a1bSJed Brown       } else {
344c4762a1bSJed Brown         xl = x[row-1];
345c4762a1bSJed Brown       }
346c4762a1bSJed Brown 
347c4762a1bSJed Brown       if (j==0) {
348c4762a1bSJed Brown         xb=user->bottom[i+1];
349c4762a1bSJed Brown         xrb = user->bottom[i+2];
350c4762a1bSJed Brown       } else {
351c4762a1bSJed Brown         xb = x[row-mx];
352c4762a1bSJed Brown       }
353c4762a1bSJed Brown 
354c4762a1bSJed Brown       if (i+1 == mx) {
355c4762a1bSJed Brown         xr=user->right[j+1];
356c4762a1bSJed Brown         xrb = user->right[j];
357c4762a1bSJed Brown       } else {
358c4762a1bSJed Brown         xr = x[row+1];
359c4762a1bSJed Brown       }
360c4762a1bSJed Brown 
361c4762a1bSJed Brown       if (j+1==my) {
362c4762a1bSJed Brown         xt=user->top[i+1];
363c4762a1bSJed Brown         xlt = user->top[i];
364c4762a1bSJed Brown       }else {
365c4762a1bSJed Brown         xt = x[row+mx];
366c4762a1bSJed Brown       }
367c4762a1bSJed Brown 
368c4762a1bSJed Brown       if (i>0 && j+1<my) {
369c4762a1bSJed Brown         xlt = x[row-1+mx];
370c4762a1bSJed Brown       }
371c4762a1bSJed Brown       if (j>0 && i+1<mx) {
372c4762a1bSJed Brown         xrb = x[row+1-mx];
373c4762a1bSJed Brown       }
374c4762a1bSJed Brown 
375c4762a1bSJed Brown       d1 = (xc-xl)*rhx;
376c4762a1bSJed Brown       d2 = (xc-xr)*rhx;
377c4762a1bSJed Brown       d3 = (xc-xt)*rhy;
378c4762a1bSJed Brown       d4 = (xc-xb)*rhy;
379c4762a1bSJed Brown       d5 = (xrb-xr)*rhy;
380c4762a1bSJed Brown       d6 = (xrb-xb)*rhx;
381c4762a1bSJed Brown       d7 = (xlt-xl)*rhy;
382c4762a1bSJed Brown       d8 = (xlt-xt)*rhx;
383c4762a1bSJed Brown 
384c4762a1bSJed Brown       f1 = PetscSqrtScalar(1.0 + d1*d1 + d7*d7);
385c4762a1bSJed Brown       f2 = PetscSqrtScalar(1.0 + d1*d1 + d4*d4);
386c4762a1bSJed Brown       f3 = PetscSqrtScalar(1.0 + d3*d3 + d8*d8);
387c4762a1bSJed Brown       f4 = PetscSqrtScalar(1.0 + d3*d3 + d2*d2);
388c4762a1bSJed Brown       f5 = PetscSqrtScalar(1.0 + d2*d2 + d5*d5);
389c4762a1bSJed Brown       f6 = PetscSqrtScalar(1.0 + d4*d4 + d6*d6);
390c4762a1bSJed Brown 
391c4762a1bSJed Brown       hl = (-hydhx*(1.0+d7*d7)+d1*d7)/(f1*f1*f1)+(-hydhx*(1.0+d4*d4)+d1*d4)/(f2*f2*f2);
392c4762a1bSJed Brown       hr = (-hydhx*(1.0+d5*d5)+d2*d5)/(f5*f5*f5)+(-hydhx*(1.0+d3*d3)+d2*d3)/(f4*f4*f4);
393c4762a1bSJed Brown       ht = (-hxdhy*(1.0+d8*d8)+d3*d8)/(f3*f3*f3)+(-hxdhy*(1.0+d2*d2)+d2*d3)/(f4*f4*f4);
394c4762a1bSJed Brown       hb = (-hxdhy*(1.0+d6*d6)+d4*d6)/(f6*f6*f6)+(-hxdhy*(1.0+d1*d1)+d1*d4)/(f2*f2*f2);
395c4762a1bSJed Brown 
396c4762a1bSJed Brown       hbr = -d2*d5/(f5*f5*f5) - d4*d6/(f6*f6*f6);
397c4762a1bSJed Brown       htl = -d1*d7/(f1*f1*f1) - d3*d8/(f3*f3*f3);
398c4762a1bSJed Brown 
399c4762a1bSJed Brown       hc = hydhx*(1.0+d7*d7)/(f1*f1*f1) + hxdhy*(1.0+d8*d8)/(f3*f3*f3) + hydhx*(1.0+d5*d5)/(f5*f5*f5) + hxdhy*(1.0+d6*d6)/(f6*f6*f6) +
400c4762a1bSJed Brown            (hxdhy*(1.0+d1*d1)+hydhx*(1.0+d4*d4)-2*d1*d4)/(f2*f2*f2) +  (hxdhy*(1.0+d2*d2)+hydhx*(1.0+d3*d3)-2*d2*d3)/(f4*f4*f4);
401c4762a1bSJed Brown 
402c4762a1bSJed Brown       hl*=0.5; hr*=0.5; ht*=0.5; hb*=0.5; hbr*=0.5; htl*=0.5;  hc*=0.5;
403c4762a1bSJed Brown 
404c4762a1bSJed Brown       k=0;
405c4762a1bSJed Brown       if (j>0) {
406c4762a1bSJed Brown         v[k]=hb; col[k]=row - mx; k++;
407c4762a1bSJed Brown       }
408c4762a1bSJed Brown 
409c4762a1bSJed Brown       if (j>0 && i < mx -1) {
410c4762a1bSJed Brown         v[k]=hbr; col[k]=row - mx+1; k++;
411c4762a1bSJed Brown       }
412c4762a1bSJed Brown 
413c4762a1bSJed Brown       if (i>0) {
414c4762a1bSJed Brown         v[k]= hl; col[k]=row - 1; k++;
415c4762a1bSJed Brown       }
416c4762a1bSJed Brown 
417c4762a1bSJed Brown       v[k]= hc; col[k]=row; k++;
418c4762a1bSJed Brown 
419c4762a1bSJed Brown       if (i < mx-1) {
420c4762a1bSJed Brown         v[k]= hr; col[k]=row+1; k++;
421c4762a1bSJed Brown       }
422c4762a1bSJed Brown 
423c4762a1bSJed Brown       if (i>0 && j < my-1) {
424c4762a1bSJed Brown         v[k]= htl; col[k] = row+mx-1; k++;
425c4762a1bSJed Brown       }
426c4762a1bSJed Brown 
427c4762a1bSJed Brown       if (j < my-1) {
428c4762a1bSJed Brown         v[k]= ht; col[k] = row+mx; k++;
429c4762a1bSJed Brown       }
430c4762a1bSJed Brown 
431c4762a1bSJed Brown       /*
432c4762a1bSJed Brown          Set matrix values using local numbering, which was defined
433c4762a1bSJed Brown          earlier, in the main routine.
434c4762a1bSJed Brown       */
4359566063dSJacob Faibussowitsch       PetscCall(MatSetValues(Hessian,1,&row,k,col,v,INSERT_VALUES));
436c4762a1bSJed Brown     }
437c4762a1bSJed Brown   }
438c4762a1bSJed Brown 
439c4762a1bSJed Brown   /* Restore vectors */
4409566063dSJacob Faibussowitsch   PetscCall(VecRestoreArrayRead(X,&x));
441c4762a1bSJed Brown 
442c4762a1bSJed Brown   /* Assemble the matrix */
4439566063dSJacob Faibussowitsch   PetscCall(MatAssemblyBegin(Hessian,MAT_FINAL_ASSEMBLY));
4449566063dSJacob Faibussowitsch   PetscCall(MatAssemblyEnd(Hessian,MAT_FINAL_ASSEMBLY));
445c4762a1bSJed Brown 
4469566063dSJacob Faibussowitsch   PetscCall(PetscLogFlops(199.0*mx*my));
447c4762a1bSJed Brown   PetscFunctionReturn(0);
448c4762a1bSJed Brown }
449c4762a1bSJed Brown 
450c4762a1bSJed Brown /* ------------------------------------------------------------------- */
451c4762a1bSJed Brown /*
452c4762a1bSJed Brown    MSA_BoundaryConditions -  Calculates the boundary conditions for
453c4762a1bSJed Brown    the region.
454c4762a1bSJed Brown 
455c4762a1bSJed Brown    Input Parameter:
456c4762a1bSJed Brown .  user - user-defined application context
457c4762a1bSJed Brown 
458c4762a1bSJed Brown    Output Parameter:
459c4762a1bSJed Brown .  user - user-defined application context
460c4762a1bSJed Brown */
461c4762a1bSJed Brown static PetscErrorCode MSA_BoundaryConditions(AppCtx * user)
462c4762a1bSJed Brown {
463c4762a1bSJed Brown   PetscInt       i,j,k,limit=0;
464c4762a1bSJed Brown   PetscInt       maxits=5;
465c4762a1bSJed Brown   PetscInt       mx=user->mx,my=user->my;
466c4762a1bSJed Brown   PetscInt       bsize=0, lsize=0, tsize=0, rsize=0;
467c4762a1bSJed Brown   PetscReal      one=1.0, two=2.0, three=3.0, tol=1e-10;
468c4762a1bSJed Brown   PetscReal      fnorm,det,hx,hy,xt=0,yt=0;
469c4762a1bSJed Brown   PetscReal      u1,u2,nf1,nf2,njac11,njac12,njac21,njac22;
470c4762a1bSJed Brown   PetscReal      b=-0.5, t=0.5, l=-0.5, r=0.5;
471c4762a1bSJed Brown   PetscReal      *boundary;
472c4762a1bSJed Brown 
473c4762a1bSJed Brown   PetscFunctionBeginUser;
474c4762a1bSJed Brown   bsize=mx+2; lsize=my+2; rsize=my+2; tsize=mx+2;
475c4762a1bSJed Brown 
4769566063dSJacob Faibussowitsch   PetscCall(PetscMalloc1(bsize,&user->bottom));
4779566063dSJacob Faibussowitsch   PetscCall(PetscMalloc1(tsize,&user->top));
4789566063dSJacob Faibussowitsch   PetscCall(PetscMalloc1(lsize,&user->left));
4799566063dSJacob Faibussowitsch   PetscCall(PetscMalloc1(rsize,&user->right));
480c4762a1bSJed Brown 
481c4762a1bSJed Brown   hx= (r-l)/(mx+1); hy=(t-b)/(my+1);
482c4762a1bSJed Brown 
483c4762a1bSJed Brown   for (j=0; j<4; j++) {
484c4762a1bSJed Brown     if (j==0) {
485c4762a1bSJed Brown       yt=b;
486c4762a1bSJed Brown       xt=l;
487c4762a1bSJed Brown       limit=bsize;
488c4762a1bSJed Brown       boundary=user->bottom;
489c4762a1bSJed Brown     } else if (j==1) {
490c4762a1bSJed Brown       yt=t;
491c4762a1bSJed Brown       xt=l;
492c4762a1bSJed Brown       limit=tsize;
493c4762a1bSJed Brown       boundary=user->top;
494c4762a1bSJed Brown     } else if (j==2) {
495c4762a1bSJed Brown       yt=b;
496c4762a1bSJed Brown       xt=l;
497c4762a1bSJed Brown       limit=lsize;
498c4762a1bSJed Brown       boundary=user->left;
499c4762a1bSJed Brown     } else {  /*  if (j==3) */
500c4762a1bSJed Brown       yt=b;
501c4762a1bSJed Brown       xt=r;
502c4762a1bSJed Brown       limit=rsize;
503c4762a1bSJed Brown       boundary=user->right;
504c4762a1bSJed Brown     }
505c4762a1bSJed Brown 
506c4762a1bSJed Brown     for (i=0; i<limit; i++) {
507c4762a1bSJed Brown       u1=xt;
508c4762a1bSJed Brown       u2=-yt;
509c4762a1bSJed Brown       for (k=0; k<maxits; k++) {
510c4762a1bSJed Brown         nf1=u1 + u1*u2*u2 - u1*u1*u1/three-xt;
511c4762a1bSJed Brown         nf2=-u2 - u1*u1*u2 + u2*u2*u2/three-yt;
512c4762a1bSJed Brown         fnorm=PetscSqrtScalar(nf1*nf1+nf2*nf2);
513c4762a1bSJed Brown         if (fnorm <= tol) break;
514c4762a1bSJed Brown         njac11=one+u2*u2-u1*u1;
515c4762a1bSJed Brown         njac12=two*u1*u2;
516c4762a1bSJed Brown         njac21=-two*u1*u2;
517c4762a1bSJed Brown         njac22=-one - u1*u1 + u2*u2;
518c4762a1bSJed Brown         det = njac11*njac22-njac21*njac12;
519c4762a1bSJed Brown         u1 = u1-(njac22*nf1-njac12*nf2)/det;
520c4762a1bSJed Brown         u2 = u2-(njac11*nf2-njac21*nf1)/det;
521c4762a1bSJed Brown       }
522c4762a1bSJed Brown 
523c4762a1bSJed Brown       boundary[i]=u1*u1-u2*u2;
524c4762a1bSJed Brown       if (j==0 || j==1) {
525c4762a1bSJed Brown         xt=xt+hx;
526c4762a1bSJed Brown       } else { /*  if (j==2 || j==3) */
527c4762a1bSJed Brown         yt=yt+hy;
528c4762a1bSJed Brown       }
529c4762a1bSJed Brown     }
530c4762a1bSJed Brown   }
531c4762a1bSJed Brown   PetscFunctionReturn(0);
532c4762a1bSJed Brown }
533c4762a1bSJed Brown 
534c4762a1bSJed Brown /* ------------------------------------------------------------------- */
535c4762a1bSJed Brown /*
536c4762a1bSJed Brown    MSA_InitialPoint - Calculates the initial guess in one of three ways.
537c4762a1bSJed Brown 
538c4762a1bSJed Brown    Input Parameters:
539c4762a1bSJed Brown .  user - user-defined application context
540c4762a1bSJed Brown .  X - vector for initial guess
541c4762a1bSJed Brown 
542c4762a1bSJed Brown    Output Parameters:
543c4762a1bSJed Brown .  X - newly computed initial guess
544c4762a1bSJed Brown */
545c4762a1bSJed Brown static PetscErrorCode MSA_InitialPoint(AppCtx * user, Vec X)
546c4762a1bSJed Brown {
547c4762a1bSJed Brown   PetscInt       start=-1,i,j;
548c4762a1bSJed Brown   PetscReal      zero=0.0;
549c4762a1bSJed Brown   PetscBool      flg;
550c4762a1bSJed Brown 
551c4762a1bSJed Brown   PetscFunctionBeginUser;
5529566063dSJacob Faibussowitsch   PetscCall(VecSet(X, zero));
5539566063dSJacob Faibussowitsch   PetscCall(PetscOptionsGetInt(NULL,NULL,"-start",&start,&flg));
554c4762a1bSJed Brown 
555c4762a1bSJed Brown   if (flg && start==0) { /* The zero vector is reasonable */
5569566063dSJacob Faibussowitsch      PetscCall(VecSet(X, zero));
557c4762a1bSJed Brown    } else { /* Take an average of the boundary conditions */
558c4762a1bSJed Brown     PetscInt    row;
559c4762a1bSJed Brown     PetscInt    mx=user->mx,my=user->my;
560c4762a1bSJed Brown     PetscReal *x;
561c4762a1bSJed Brown 
562c4762a1bSJed Brown     /* Get pointers to vector data */
5639566063dSJacob Faibussowitsch     PetscCall(VecGetArray(X,&x));
564c4762a1bSJed Brown     /* Perform local computations */
565c4762a1bSJed Brown     for (j=0; j<my; j++) {
566c4762a1bSJed Brown       for (i=0; i< mx; i++) {
567c4762a1bSJed Brown         row=(j)*mx + (i);
568c4762a1bSJed Brown         x[row] = (((j+1)*user->bottom[i+1]+(my-j+1)*user->top[i+1])/(my+2)+ ((i+1)*user->left[j+1]+(mx-i+1)*user->right[j+1])/(mx+2))/2.0;
569c4762a1bSJed Brown       }
570c4762a1bSJed Brown     }
571c4762a1bSJed Brown     /* Restore vectors */
5729566063dSJacob Faibussowitsch     PetscCall(VecRestoreArray(X,&x));
573c4762a1bSJed Brown   }
574c4762a1bSJed Brown   PetscFunctionReturn(0);
575c4762a1bSJed Brown }
576c4762a1bSJed Brown 
577c4762a1bSJed Brown /*TEST
578c4762a1bSJed Brown 
579c4762a1bSJed Brown    build:
580c4762a1bSJed Brown       requires: !complex
581c4762a1bSJed Brown 
582c4762a1bSJed Brown    test:
583c4762a1bSJed Brown       args: -tao_smonitor -tao_type nls -mx 10 -my 8 -tao_gatol 1.e-4
584c4762a1bSJed Brown       requires: !single
585c4762a1bSJed Brown 
586c4762a1bSJed Brown    test:
587c4762a1bSJed Brown       suffix: 2
588c4762a1bSJed Brown       args: -tao_smonitor -tao_type bmrm -mx 10 -my 8 -tao_gatol 1.e-3
589c4762a1bSJed Brown       requires: !single
590c4762a1bSJed Brown 
591c4762a1bSJed Brown    test:
592c4762a1bSJed Brown       suffix: 3
593c4762a1bSJed Brown       args: -tao_smonitor -tao_type lmvm -mx 10 -my 8 -tao_gatol 1.e-3
594c4762a1bSJed Brown       requires: !single
595c4762a1bSJed Brown 
596c4762a1bSJed Brown    test:
597c4762a1bSJed Brown       suffix: 4
598c4762a1bSJed Brown       args: -tao_smonitor -tao_type bntr -mx 10 -my 8 -tao_gatol 1.e-4
599c4762a1bSJed Brown       requires: !single
600c4762a1bSJed Brown 
601c4762a1bSJed Brown    test:
6020f0abf79SStefano Zampini       suffix: 4_ew
6030f0abf79SStefano Zampini       args: -tao_smonitor -tao_type bntr -tao_ksp_ew -mx 10 -my 8 -tao_gatol 1.e-4
6040f0abf79SStefano Zampini       requires: !single
6050f0abf79SStefano Zampini 
6060f0abf79SStefano Zampini    test:
607c4762a1bSJed Brown       suffix: 5
608c4762a1bSJed Brown       args: -tao_smonitor -tao_type bntl -mx 10 -my 8 -tao_gatol 1.e-4
609c4762a1bSJed Brown       requires: !single
610c4762a1bSJed Brown 
611c4762a1bSJed Brown    test:
6120f0abf79SStefano Zampini       suffix: 5_ew
6130f0abf79SStefano Zampini       args: -tao_smonitor -tao_type bntl -tao_ksp_ew -mx 10 -my 8 -tao_gatol 1.e-4
6140f0abf79SStefano Zampini       requires: !single
6150f0abf79SStefano Zampini 
6160f0abf79SStefano Zampini    test:
617c4762a1bSJed Brown       suffix: 6
618c4762a1bSJed Brown       args: -tao_smonitor -tao_type bnls -mx 10 -my 8 -tao_gatol 1.e-4
619c4762a1bSJed Brown       requires: !single
620c4762a1bSJed Brown 
621c4762a1bSJed Brown    test:
6220f0abf79SStefano Zampini       suffix: 6_ew
6230f0abf79SStefano Zampini       args: -tao_smonitor -tao_type bnls -tao_ksp_ew -tao_bnk_ksp_ew_version 3 -mx 10 -my 8 -tao_gatol 1.e-4
6240f0abf79SStefano Zampini       requires: !single
6250f0abf79SStefano Zampini 
6260f0abf79SStefano Zampini    test:
627c4762a1bSJed Brown       suffix: 7
628c4762a1bSJed Brown       args: -tao_smonitor -tao_type bntr -mx 10 -my 8 -tao_bnk_max_cg_its 3 -tao_gatol 1.e-4
629c4762a1bSJed Brown       requires: !single
630c4762a1bSJed Brown 
631c4762a1bSJed Brown    test:
632c4762a1bSJed Brown       suffix: 8
633c4762a1bSJed Brown       args: -tao_smonitor -tao_type bntl -mx 10 -my 8 -tao_bnk_max_cg_its 3 -tao_gatol 1.e-4
634c4762a1bSJed Brown       requires: !single
635c4762a1bSJed Brown 
636c4762a1bSJed Brown    test:
637c4762a1bSJed Brown       suffix: 9
638c4762a1bSJed Brown       args: -tao_smonitor -tao_type bnls -mx 10 -my 8 -tao_bnk_max_cg_its 3 -tao_gatol 1.e-4
639c4762a1bSJed Brown       requires: !single
640c4762a1bSJed Brown 
64134ad9904SAlp Dener    test:
64234ad9904SAlp Dener       suffix: 10
64334ad9904SAlp Dener       args: -tao_smonitor -tao_type bnls -mx 10 -my 8 -tao_bnk_max_cg_its 3 -tao_gatol 1.e-4 -tao_mf_hessian
64434ad9904SAlp Dener 
64534ad9904SAlp Dener    test:
64634ad9904SAlp Dener       suffix: 11
64734ad9904SAlp Dener       args: -tao_smonitor -tao_type bntr -mx 10 -my 8 -tao_gatol 1.e-4 -tao_mf_hessian
64834ad9904SAlp Dener       requires: !single
64934ad9904SAlp Dener 
65034ad9904SAlp Dener    test:
65134ad9904SAlp Dener       suffix: 12
65234ad9904SAlp Dener       args: -tao_smonitor -tao_type bntl -mx 10 -my 8 -tao_gatol 1.e-4 -tao_mf_hessian
65334ad9904SAlp Dener       requires: !single
65434ad9904SAlp Dener 
655c4762a1bSJed Brown TEST*/
656