gpusample/cpp/sample3.cpp at main · cfcanaoj/gpusample · GitHub

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#include <iostream>
#include <fstream>
#include <cstdlib>
#include <ctime>
#include <cmath>

#include <vector>

void InitializeVariables();
void SetupGrids();
void SetupDensity();
void GetGravitationalPotential();
void OutputData();

namespace grids{
  const double Ggra=1.0e0;
  const double rho0=1.0e0;
  double pi;
  double x1min,x1max;
  double x2min,x2max;

  const int margin=1;
  const int nx1=1024;
  const int nx2=1024;

  double dx1;
  std::vector<double>  x1a(nx1+1);
  std::vector<double>  x1b(nx1),dvl1a(nx1);

  double dx2;
  std::vector<double>  x2a(nx2+1);
  std::vector<double>  x2b(nx2),dvl2a(nx1);

  std::vector<double>  rho(nx1*nx2),gp(nx1*nx2);

  const int l1=1;
  const int l2=1;
  const double persymx1=-1.0;
  const double persymx2=-1.0;

  const int itemax=300;
};

int main(int argc, char**argv){
  clock_t start,stop;
  printf("CPU:\n");
  InitializeVariables();
  SetupGrids();
  SetupDensity();
  start=clock();
  GetGravitationalPotential();
  stop=clock();
  OutputData();
  printf("Time: %.2f [ms]\n",(double)(stop-start));
}

void InitializeVariables(){
}

void SetupGrids(){
  using namespace grids;
  int i,j;
  x1min = 0.0e0;
  x1max = 1.0e0;
  x2min = 0.0e0;
  x2max = 1.0e0;

  dx1 =(x1max-x1min)/(nx1-margin*2);
  x1a[0] = x1min -margin*dx1;
  for(i=1;i<=nx1;i++){
    x1a[i] =x1a[i-1] + dx1;
  }
  for(i=0;i<nx1;i++){
    x1b[i] = 0.5e0*(x1a[i] + x1a[i]);
  dvl1a[i] = dx1;
  }

  dx2 =(x2max-x2min)/(nx2-margin*2);
  x2a[0] =x2min -margin*dx2;
  for(j=1;j<=nx2;j++){
    x2a[j] =x2a[j-1] + dx2;
  }
  for(j=0;j<nx2;j++){
      x2b[j] = 0.5e0*(x2a[j] + x2a[j]);
    dvl2a[j] = dx2;
  }

}

void SetupDensity(){
  using namespace grids;
  int i,j;
  pi =atan2(0.0,-1.0);
  for(j=0;j<nx2;j++){
  for(i=0;i<nx1;i++){
       rho[j*nx1+i] = rho0 * sin(l1*pi*x1b[i]/(x1max-x1min))
                           * sin(l2*pi*x2b[j]/(x2max-x2min));
  }
  }
}

void GetGravitationalPotential(){
  using namespace grids;
  std::vector<double>  gpnxt(nx1*nx2);
  double  a1,a2,a3;
  int  i,j,n;
  a1 = 1.0e0/dx1/dx1;
  a2 = 1.0e0/dx2/dx2;
  a3 = 2.0e0*(a1+a2);

  for(n=0;n<itemax;n++){

  for(j=1;j<nx2-1;j++){
  for(i=1;i<nx1-1;i++){
     gpnxt[j*nx1+i] = ( a1*(gp[    j*nx1+i+1]+gp[    j*nx1+i-1])
		       +a2*(gp[(j+1)*nx1+i  ]+gp[(j-1)*nx1+i  ])
                              -4.0e0*pi*Ggra*rho[    j*nx1+i  ]
		      )/a3;

  }
  }

  for(j=1;j<nx2-1;j++){
  for(i=1;i<nx1-1;i++){
     gp[j*nx1+i] = gpnxt[j*nx1+i];
  }
  }
  for(i=0;i<nx1;i++){
     gp[      0*nx1+i] = persymx2*gp[(nx2-2)*nx1+i];
     gp[(nx2-1)*nx1+i] = persymx2*gp[(    1)*nx1+i];
  }
  for(j=0;j<nx2;j++){
     gp[      j*nx1+0    ] = persymx1*gp[  j*nx1+nx1-2];
     gp[      j*nx1+nx1-1] = persymx1*gp[  j*nx1+    1];
  }

  } /* n-loop*/
}

void OutputData(){
  using namespace grids;
  int  i,j;
  static FILE *fp;
  const char filename[30]="xy-cpu.dat";
  fp=fopen(filename,"w");
  for(j=1;j<nx2-1;j++){
  for(i=1;i<nx1-1;i++){
    fprintf(fp," %e %e %e %e\n",x1b[i], x2b[j],rho[j*nx1+i],gp[j*nx1+i]);
  }
    fprintf(fp,"\n");
  }
  fclose(fp);
}