/* CReate a file and use nccd_def_file to annotate it. */
if (nc_create(FILE_NAME_SIMPLE_SIGMA, 0, &ncid)) ERR;
if (nccf_def_file(ncid, TITLE, HISTORY)) ERR;
if (nccf_def_latitude(ncid, NLATS, NC_INT, &lat_did,
&lat_vid)) ERR;
if (nccf_def_longitude(ncid, NLONS, NC_INT, &lon_did,
&lon_vid)) ERR;
/* Now define sigma level coordinage var and dim. */
if (nccf_def_lvl_sigma(ncid, "sigma", NC_FLOAT, NLVLS,
&lvl_did, &lvl_vid)) ERR;
/* Now define the time coordinate. */
if (nccf_def_time(ncid, "time", NC_UNLIMITED, NC_FLOAT, TIME_UNITS,
"time", &time_did, &time_vid)) ERR;
/* Before we can set the sigma level formula terms, we
* need to define two variables, the surface pressure and PTOP
* (a scalar).*/
dimids[0] = lat_did;
dimids[1] = lon_did;
if (nc_def_var(ncid, "ps", NC_FLOAT, 2, dimids, &ps_vid)) ERR;
if (nc_def_var(ncid, "PTOP", NC_FLOAT, 0, NULL, &ptop_vid)) ERR;
/* Save the ps and ptop info in the formula terms attribute. */
if (nccf_def_ft_sigma(ncid, lvl_vid, ps_vid, ptop_vid)) ERR;
/* Now create a data variable. */
dimids[0] = time_did;
dimids[1] = lvl_did;
dimids[2] = lat_did;
dimids[3] = lon_did;
if (nc_def_var(ncid, "data", NC_FLOAT, NDIMS, dimids, &data_vid)) ERR;
/* End define mode. */
if (nc_enddef(ncid)) ERR;
/* Write lats and lons. */
if (nc_put_var_int(ncid, lat_vid, lat)) ERR;
if (nc_put_var_int(ncid, lon_vid, lon)) ERR;