1 #define PETSCTS_DLL 2 3 /* 4 Code for Timestepping with explicit Euler. 5 */ 6 #include "include/private/tsimpl.h" /*I "petscts.h" I*/ 7 8 typedef struct { 9 Vec update; /* work vector where F(t[i],u[i]) is stored */ 10 } TS_Euler; 11 12 #undef __FUNCT__ 13 #define __FUNCT__ "TSSetUp_Euler" 14 static PetscErrorCode TSSetUp_Euler(TS ts) 15 { 16 TS_Euler *euler = (TS_Euler*)ts->data; 17 PetscErrorCode ierr; 18 19 PetscFunctionBegin; 20 ierr = VecDuplicate(ts->vec_sol,&euler->update);CHKERRQ(ierr); 21 PetscFunctionReturn(0); 22 } 23 24 #undef __FUNCT__ 25 #define __FUNCT__ "TSStep_Euler" 26 static PetscErrorCode TSStep_Euler(TS ts,PetscInt *steps,PetscReal *ptime) 27 { 28 TS_Euler *euler = (TS_Euler*)ts->data; 29 Vec sol = ts->vec_sol,update = euler->update; 30 PetscErrorCode ierr; 31 PetscInt i,max_steps = ts->max_steps; 32 PetscScalar dt = ts->time_step; 33 34 PetscFunctionBegin; 35 *steps = -ts->steps; 36 ierr = TSMonitor(ts,ts->steps,ts->ptime,sol);CHKERRQ(ierr); 37 38 for (i=0; i<max_steps; i++) { 39 ts->ptime += ts->time_step; 40 ierr = TSComputeRHSFunction(ts,ts->ptime,sol,update);CHKERRQ(ierr); 41 ierr = VecAXPY(sol,dt,update);CHKERRQ(ierr); 42 ts->steps++; 43 ierr = TSMonitor(ts,ts->steps,ts->ptime,sol);CHKERRQ(ierr); 44 if (ts->ptime > ts->max_time) break; 45 } 46 47 *steps += ts->steps; 48 *ptime = ts->ptime; 49 PetscFunctionReturn(0); 50 } 51 /*------------------------------------------------------------*/ 52 #undef __FUNCT__ 53 #define __FUNCT__ "TSDestroy_Euler" 54 static PetscErrorCode TSDestroy_Euler(TS ts) 55 { 56 TS_Euler *euler = (TS_Euler*)ts->data; 57 PetscErrorCode ierr; 58 59 PetscFunctionBegin; 60 if (euler->update) {ierr = VecDestroy(euler->update);CHKERRQ(ierr);} 61 ierr = PetscFree(euler);CHKERRQ(ierr); 62 PetscFunctionReturn(0); 63 } 64 /*------------------------------------------------------------*/ 65 66 #undef __FUNCT__ 67 #define __FUNCT__ "TSSetFromOptions_Euler" 68 static PetscErrorCode TSSetFromOptions_Euler(TS ts) 69 { 70 PetscFunctionBegin; 71 PetscFunctionReturn(0); 72 } 73 74 #undef __FUNCT__ 75 #define __FUNCT__ "TSView_Euler" 76 static PetscErrorCode TSView_Euler(TS ts,PetscViewer viewer) 77 { 78 PetscFunctionBegin; 79 PetscFunctionReturn(0); 80 } 81 82 /* ------------------------------------------------------------ */ 83 84 /*MC 85 TS_EULER - ODE solver using the explicit forward Euler method 86 87 Level: beginner 88 89 .seealso: TSCreate(), TS, TSSetType(), TS_BEULER 90 91 M*/ 92 EXTERN_C_BEGIN 93 #undef __FUNCT__ 94 #define __FUNCT__ "TSCreate_Euler" 95 PetscErrorCode PETSCTS_DLLEXPORT TSCreate_Euler(TS ts) 96 { 97 TS_Euler *euler; 98 PetscErrorCode ierr; 99 100 PetscFunctionBegin; 101 ts->ops->setup = TSSetUp_Euler; 102 ts->ops->step = TSStep_Euler; 103 ts->ops->destroy = TSDestroy_Euler; 104 ts->ops->setfromoptions = TSSetFromOptions_Euler; 105 ts->ops->view = TSView_Euler; 106 107 ierr = PetscNewLog(ts,TS_Euler,&euler);CHKERRQ(ierr); 108 ts->data = (void*)euler; 109 110 PetscFunctionReturn(0); 111 } 112 EXTERN_C_END 113 114 115 116 117