<div style="line-height:1.7;color:#000000;font-size:14px;font-family:arial">/* Program usage:  mpiexec ex1 [-help] [all PETSc options] */<br><br>static char help[] = "Basic vector routines.\n\n";<br><br><br>#include "petscksp.h"<br>#include "petscvec.h"<br><br><br><br>int main(int argc,char **argv)<br>{<br>  int N=16;<br>  <br>  int MyRank;<br>  <br>   Mat A;  <br>   PC Pc;  <br>   KSP ksp;<br>   Vec b,x;<br>  <br> PetscInitialize(&argc,&argv,(char*)0,help);<br>  MPI_Comm_rank(MPI_COMM_WORLD,&MyRank);<br>  <br>  MatCreate(PETSC_COMM_WORLD,&A);<br>  MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N);<br>  MatSetFromOptions(A);<br>  MatMPIAIJSetPreallocation(A,5,PETSC_NULL,5,PETSC_NULL);<br>  <br>  VecCreate(PETSC_COMM_WORLD,&b);<br>  VecSetSizes(b,PETSC_DECIDE,N);<br>  VecSetFromOptions(b); <br>  VecDuplicate(b,&x);<br>&n
 
 bsp; <br>  int row=0;<br>  int* col3;<br>  int* col4;<br>  int* col5;<br>  PetscMalloc(3*sizeof(PetscInt),&col3);<br>  PetscMalloc(4*sizeof(PetscInt),&col4);<br>  PetscMalloc(5*sizeof(PetscInt),&col5);<br>  <br>  col3[0]=0;  col3[1]=1;  col3[2]=4;<br> double value3[3]={2.2916666666666665e+00,-1.1458333333333333e+00,-1.1458333333333333e+00};<br> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES);<br><br> row=1;<br> col4[0]=0;  col4[1]=1;  col4[2]=2; col4[3]=5;<br> double value4[4]={-1.1458333333333333e+00,3.8020833333333330e+00,-1.2500000000000000e+00 ,-1.4062500000000000e+00};<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES);<br><br> <br>  row=2;<br> col4[0]=1;  col4[1]=2;  col4[2]=3; col4[3]=6;<br> value4[0]=-1.2500000000000000e+00;<br> value4[1]=3.8020833333333330e+00;<br> value4[2]=-1.1458333333333333e+00 ;<br>&n
 
 bsp;value4[3]=-1.4062500000000000e+00;<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES);<br> <br>  <br>   row=3;<br>  col3[0]=2;  col3[1]=3;  col3[2]=7;<br> value3[0]=-1.1458333333333333e+00;<br> value3[1]=2.2916666666666665e+00;<br> value3[2]=-1.1458333333333333e+00;<br> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES); <br> <br> <br>  row=4;<br> col4[0]=0;  col4[1]=4;  col4[2]=5; col4[3]=8;<br> value4[0]=-1.1458333333333333e+00;<br> value4[1]=3.8020833333333330e+00;<br> value4[2]=-1.4062500000000000e+00;<br> value4[3]=-1.2500000000000000e+00;<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES); <br> <br>   row=5;<br> col5[0]=1;  col5[1]=4;  col5[2]=5; col5[3]=6; col5[4]=9;<br> double value5[5];<br> value5[0]=-1.4062500000000000e+00;<br> value5[1]=-1.4062500000000000e+00;<br> value5[2]=5
 
 .9375000000000000e+00;<br> value5[3]=-1.5625000000000000e+00 ;<br> value5[4]=-1.5625000000000000e+00 ;<br>  MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES); <br> <br> <br> <br>  row=6;<br> col5[0]=2;  col5[1]=5;  col5[2]=6; col5[3]=7; col5[4]=10;<br> value5[0]=-1.4062500000000000e+00;<br> value5[1]=-1.5625000000000000e+00;<br> value5[2]=5.9375000000000000e+00;<br> value5[3]=-1.4062500000000000e+00 ;<br> value5[4]=-1.5625000000000000e+00 ;<br>  MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES);   <br>  <br>  row=7;<br> col4[0]=3;  col4[1]=6;  col4[2]=7; col4[3]=11;<br> value4[0]=-1.1458333333333333e+00;<br> value4[1]=-1.4062500000000000e+00;<br> value4[2]=3.8020833333333330e+00;<br> value4[3]=-1.2500000000000000e+00;<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES);   <br>  <br>  row=8;<br> 
 
 col4[0]=4;  col4[1]=8;  col4[2]=9; col4[3]=12;<br> value4[0]=-1.2500000000000000e+00;<br> value4[1]=3.8020833333333330e+00;<br> value4[2]=-1.4062500000000000e+00;<br> value4[3]=-1.1458333333333333e+00;<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES);     <br>  <br>  <br>   row=9;<br> col5[0]=5;  col5[1]=8;  col5[2]=9; col5[3]=10; col5[4]=13;<br> value5[0]=-1.5625000000000000e+00;<br> value5[1]=-1.4062500000000000e+00;<br> value5[2]=5.9375000000000000e+00;<br> value5[3]=-1.5625000000000000e+00 ;<br> value5[4]= -1.4062500000000000e+00;<br>  MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES);  <br>  <br>     row=10;<br> col5[0]=6;  col5[1]=9;  col5[2]=10; col5[3]=11; col5[4]=14;<br> value5[0]=-1.5625000000000000e+00;<br> value5[1]=-1.5625000000000000e+00;<br> value5[2]=5.93750000000000
 
 00e+00;<br> value5[3]=-1.4062500000000000e+00 ;<br> value5[4]= -1.4062500000000000e+00;<br>  MatSetValues(A,1,&row,5,col5,value5,INSERT_VALUES);  <br>  <br>  <br>  row=11;<br> col4[0]=7;  col4[1]=10;  col4[2]=11; col4[3]=15;<br> value4[0]=-1.2500000000000000e+00;<br> value4[1]=-1.4062500000000000e+00;<br> value4[2]=3.8020833333333330e+00;<br> value4[3]=-1.1458333333333333e+00;<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES);     <br>  <br>  <br>  <br>  <br>    row=12;<br>  col3[0]=8;  col3[1]=12;  col3[2]=13;<br> value3[0]=-1.1458333333333333e+00;<br> value3[1]=2.2916666666666665e+00;<br> value3[2]=-1.1458333333333333e+00;<br> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES);  <br>  <br>  <br>   row=13;<br> col4[0]=9;  col4[1]=12;  col4[2]=13; col4[3]=
 
 14;<br> value4[0]=-1.4062500000000000e+00;<br> value4[1]=-1.1458333333333333e+00;<br> value4[2]=3.8020833333333330e+00;<br> value4[3]=-1.2500000000000000e+00;<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES);   <br>  <br>  <br>   row=14;<br> col4[0]=10;  col4[1]=13;  col4[2]=14; col4[3]=15;<br> value4[0]=-1.4062500000000000e+00;<br> value4[1]=-1.2500000000000000e+00;<br> value4[2]=3.8020833333333330e+00;<br> value4[3]=-1.1458333333333333e+00;<br>  MatSetValues(A,1,&row,4,col4,value4,INSERT_VALUES);   <br>  <br>  <br>  <br>     row=15;<br>  col3[0]=11;  col3[1]=14;  col3[2]=15;<br> value3[0]=-1.1458333333333333e+00;<br> value3[1]=-1.1458333333333333e+00;<br> value3[2]=2.2916666666666665e+00;<br> MatSetValues(A,1,&row,3,col3,value3,INSERT_VALUES);   <br>  <br> <br>&n
 
 bsp;<br>  MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);<br>  MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);  <br>    <br>//  MatView(A,PETSC_VIEWER_STDOUT_WORLD);  <br><br> <br>  <br>  double val[16]={-7.6233779415782715e-04,<br>-3.0457072596705860e-04,<br>3.0457072596705860e-04,<br>7.6233779415782715e-04,<br>-4.4764543813290442e-03,<br>-1.6196451741044846e-03,<br>1.6196451741044846e-03,<br>4.4764543813290442e-03,<br>-1.9333475373837013e-02,<br>-5.4815619458573189e-03,<br>5.4815619458573189e-03,<br>1.9333475373837013e-02,<br>-8.4153777598326651e-02,<br>-1.2883385353962010e-02,<br>1.2883385353962010e-02,<br>8.4153777598326651e-02};<br><br>int* col16;<br>  PetscMalloc(16*sizeof(PetscInt),&col16);<br> for(int i=0;i<16;i++)<br>  col16[i]=i;<br>  <br>VecSetValues(b,16,col16,val,INSERT_VALUES);<br>    VecAssemblyBegin(b);<br>    VecAssemblyEnd(b);    <br>//<br> &nbs
 
 p;   VecView(b,PETSC_VIEWER_STDOUT_WORLD); <br><br>    <br>  KSPCreate(PETSC_COMM_WORLD,&ksp);<br>  KSPSetOperators(ksp,A,A,SAME_NONZERO_PATTERN);<br>  KSPSetOperators(ksp,A,A,SAME_PRECONDITIONER);<br>  KSPSetInitialGuessNonzero(ksp,PETSC_FALSE);<br>  <br>  KSPSetType(ksp,KSPBCGS);<br> //  KSPSetType(ksp,KSPLSQR);<br> //  KSPSetType(ksp,KSPFGMRES);<br> // KSPSetType(ksp,KSPDGMRES);<br>//KSPSetType(ksp,KSPTCQMR);<br> // KSPSetType(ksp,KSPPREONLY);<br>  <br>  //KSPGetPC(ksp,&Pc);<br> // PCSetType(Pc,PCJACOBI);<br>  KSPSetFromOptions(ksp);<br>  KSPSetTolerances(ksp,1.e-20,1.e-20,PETSC_DEFAULT,1000);<br>  KSPSolve(ksp,b,x); <br> <br>  <br>  VecView(x,PETSC_VIEWER_STDOUT_WORLD); <br><br>  <br>  PetscFinalize();<br>  return 0;<br>}<br> <br><br></div><br><br><span title="neteasefooter"><span id="netease_mail_footer"></span></s
 
 pan>