Short example of using cow functions with parallel write and FFT's. This example is from the CAL group meeting on Wednesday 7/24, after Jonathan's going away party.

cow-example.c

#include <stdio.h>
#include "cow.h"

double cheese_function(double x, double y, double z)
{
  return x + y + z;
}
double butter_function(double x, double y, double z)
{
  return x + y + z;
}
double yogurt_function(double x, double y, double z)
{
  return x + y + z;
}

int main(int argc, char **argv)
{
  cow_init(argc, argv, COW_DEFAULT);

  cow_domain *domain = cow_domain_new();
  cow_dfield *dfield = cow_dfield_new();

  cow_domain_setndim(domain, 3);
  cow_domain_setguard(domain, 3);
  cow_domain_setsize(domain, 0, 128);
  cow_domain_setsize(domain, 1, 128);
  cow_domain_setsize(domain, 2, 128);
  cow_domain_commit(domain);
  cow_domain_setcollective(domain, 0);
  cow_dfield_setdomain(dfield, domain);
  cow_dfield_setname(dfield, "dairy");
  cow_dfield_addmember(dfield, "cheese");
  cow_dfield_addmember(dfield, "butter");
  cow_dfield_addmember(dfield, "yogurt");
  cow_dfield_commit(dfield);


  double *dairy_data = (double*) cow_dfield_getdatabuffer(dfield);
  int n,i,j,k;

  int totsize = cow_domain_getnumlocalzonesincguard(domain, COW_ALL_DIMS);
  int nx = cow_domain_getnumlocalzonesinterior(domain, 0);
  int ny = cow_domain_getnumlocalzonesinterior(domain, 1);
  int nz = cow_domain_getnumlocalzonesinterior(domain, 2);
  int ng = cow_domain_getguard(domain);

  int sx = cow_dfield_getstride(dfield, 0);
  int sy = cow_dfield_getstride(dfield, 1);
  int sz = cow_dfield_getstride(dfield, 2);

  for (n=0; n<totsize; ++n) {
    dairy_data[3*n + 0] = 1.0; // cheese
    dairy_data[3*n + 1] = 2.0; // butter
    dairy_data[3*n + 2] = 3.0; // yogurt
  }

  for (i=ng; i<nx + ng; ++i) {
    for (j=ng; j<ny + ng; ++j) {
      for (k=ng; k<nz + ng; ++k) {

  double x = cow_domain_positionatindex(domain, 0, i);
	double y = cow_domain_positionatindex(domain, 1, j);
	double z = cow_domain_positionatindex(domain, 2, k);
	int m = i*sx + j*sy + k*sz;

	dairy_data[m + 0] = cheese_function(x, y, z);
	dairy_data[m + 1] = butter_function(x, y, z);
	dairy_data[m + 2] = yogurt_function(x, y, z);
      }
    }
  }

  cow_dfield_syncguard(dfield);
  cow_dfield_write(dfield, "dairy.h5");

  cow_fft_helmholtzdecomp(dfield, COW_PROJECT_OUT_CURL);

  cow_dfield_del(dfield);
  cow_domain_del(domain);

  cow_finalize();

  return 0;
}