#include <cdi.h>
#include "cdo.h"
#include "cdo_int.h"
#include "grid.h"
#include "util.h"  /* progressStatus */

#if defined(_OPENMP)
#include <omp.h>  // omp_get_thread_num()
#endif

/**
* Find the interval i-1 .. i in which an element x fits and return i, the 
* bigger one of the interval borders or x itself if it is an interval border.
*
* If no interval can be found return the length of the array.

* @param *array ascending or descending sorted list
* @param nelem  length of the sorted list
* @param x      the element to find a position for 
*/
static
long find_element(double x, long nelem, const double *restrict array)
{
  long ii;
  long mid = 0;
  long first = 1;
  long last = nelem;

  if ( array[0] < array[nelem-1] ) // ascending order
    {
      /* return the length of the array if x is out of bounds */
      if ( x < array[0] || x > array[nelem-1] ) return (nelem);

      /* search for the interval in which x fits */
      // implementation: binary search algorithm
      for ( ii = 1; ii < nelem; ++ii )
	{
	  // binary search: divide search room in the middle
	  // mid = first + ((last - first) >> 1);
	  // faster!
	  mid = (first + last) >> 1;
      
	  /* return the bigger interval border of the interval in which x fits */
	  // if ( x >= array[mid-1] && x <= array[mid] ) break;
	  // faster!
	  if ( !(x < array[mid-1] || x > array[mid]) ) break;

	  // binary search: ignore half of the search room
	  if ( x > array[mid] )
	    first = mid;
	  else
	    last = mid;
	}
    }
  else
    {
      /* return the length of the array if x is out of bounds */
      if ( x < array[nelem-1] || x > array[0] ) return (nelem);

      /* search for the interval in which x fits */
      // implementation: binary search algorithm
      for ( ii = 1; ii < nelem; ++ii )
	{
	  // binary search: divide search room in the middle
	  // mid = first + ((last - first) >> 1);
	  // faster!
	  mid = (first + last) >> 1;
      
	  /* return the bigger interval border of the interval in which x fits */
	  // if ( x >= array[mid] && x <= array[mid-1] ) break;
	  // faster!
	  if ( !(x < array[mid] || x > array[mid-1]) ) break;

	  // binary search: ignore half of the search room
	  if ( x < array[mid] )
	    first = mid;
	  else
	    last = mid;
	}
    }

  return (mid);
}
/*
static
long find_element_old(double x, long nelem, const double *array)
{
  long ii;

  if ( array[0] < array[nelem-1] )
    {
      for ( ii = 1; ii < nelem; ii++ )
	if ( x >= array[ii-1] && x <= array[ii] ) break;
    }
  else
    {
      for ( ii = 1; ii < nelem; ii++ )
	if ( x >= array[ii] && x <= array[ii-1] ) break;
    }

  return (ii);
}
*/

static
int rect_grid_search(long *ii, long *jj, double x, double y, long nxm, long nym, const double *restrict xm, const double *restrict ym)
{
  int lfound = 0;

  *jj = find_element(y, nym, ym);
	  
  if ( *jj < nym )
    {
      *ii = find_element(x, nxm, xm);
	  
      if ( *ii < nxm ) lfound = 1;
    }

  return (lfound);
}

static
int rect_grid_search2(long *imin, long *imax, double xmin, double xmax, long nxm, const double *restrict xm)
{
  int lfound = 0;
  int lascend = 0;
  long i;
  *imin = nxm;
  *imax = -1;
  
  if ( xm[0] < xm[nxm-1] ) lascend = 1;

  i = find_element(xmin, nxm, xm);

  if ( i > 0 && i < nxm )
    {
      lfound = 1;

      if ( lascend )
	{
	  if ( i > 1 && xmin <= xm[i-1] ) i--;
	  *imin = i-1;
	  *imax = i-1;
	}
      else
	{
	  if ( i > 1 && i < nxm-2 && xmin <= xm[i+1] ) i++;   
	  *imin = i-1;
	  *imax = i-1;
	}

      i = find_element(xmax, nxm, xm);

      if ( i > 0 && i < nxm )
	{
	  if ( lascend )
	    {
	      if ( i > 1 && i < nxm-2 && xmax >= xm[i+1] ) i++;   
	      *imax = i-1;
	    }
	  else
	    {
	      if ( i > 1 && xmax >= xm[i-1] ) i--;
	      *imin = i-1;
	    }
	}
    }
  
  return (lfound);
}


double intlinarr2p(long nxm, long nym, double **fieldm, const double *xm, const double *ym,
		   double x, double y)
{
  long ii, jj;
  double value = 0;

  for ( jj = 1; jj < nym; jj++ )
    if ( y >= MIN(ym[jj-1], ym[jj]) && y <= MAX(ym[jj-1], ym[jj]) ) break;

  for ( ii = 1; ii < nxm; ii++ )
    if ( x >= xm[ii-1] && x <= xm[ii] ) break;

  if ( jj < nym && ii < nxm )
    {
      value = fieldm[jj-1][ii-1] * (x-xm[ii]) * (y-ym[jj])
	          / ((xm[ii-1]-xm[ii]) * (ym[jj-1]-ym[jj]))
            + fieldm[jj-1][ii] * (x-xm[ii-1]) * (y-ym[jj])
                  / ((xm[ii]-xm[ii-1]) * (ym[jj-1]-ym[jj]))
            + fieldm[jj][ii-1] * (x-xm[ii]) * (y-ym[jj-1])
                  / ((xm[ii-1]-xm[ii]) * (ym[jj]-ym[jj-1]))
            + fieldm[jj][ii] * (x-xm[ii-1]) * (y-ym[jj-1])
                  / ((xm[ii]-xm[ii-1]) * (ym[jj]-ym[jj-1]));
    }

  return value;
}

static
void intlinarr2(double missval, int lon_is_circular,
		long nxm, long nym,  const double *restrict fieldm, const double *restrict xm, const double *restrict ym,
		long gridsize2, double *field, const double *restrict x, const double *restrict y)
{
  long i, ii, jj;
  long gridsize1;
  long nlon1 = nxm;
  double findex = 0;
  int *grid1_mask = NULL;

  if ( lon_is_circular ) nlon1--;
  gridsize1 = nlon1*nym;

  grid1_mask = (int *) calloc(1, gridsize1*sizeof(int));
  for ( jj = 0; jj < nym; ++jj )
    for ( ii = 0; ii < nlon1; ++ii )
      {
	if ( !DBL_IS_EQUAL(fieldm[jj*nlon1+ii], missval) ) grid1_mask[jj*nlon1+ii] = 1;
      }

  progressInit();

#if defined(_OPENMP)
#pragma omp parallel for default(none) \
  shared(ompNumThreads, field, fieldm, x, y, xm, ym, nxm, nym, gridsize2, missval, findex, nlon1, lon_is_circular, grid1_mask) \
  private(i, jj, ii)
#endif
  for ( i = 0; i < gridsize2; ++i )
    {
      int src_add[4];                /*  address for the four source points    */
      long n;
      long iix;
      int lfound;
      int lprogress = 1;
#if defined(_OPENMP)
      if ( omp_get_thread_num() != 0 ) lprogress = 0;
#endif

      field[i] = missval;

#if defined(_OPENMP)
#pragma omp atomic
#endif
      findex++;
      if ( lprogress ) progressStatus(0, 1, findex/gridsize2);

      lfound = rect_grid_search(&ii, &jj, x[i], y[i], nxm, nym, xm, ym); 

      if ( lfound )
	{
	  iix = ii;
	  if ( lon_is_circular && iix == (nxm-1) ) iix = 0;
	  src_add[0] = (jj-1)*nlon1+(ii-1);
	  src_add[1] = (jj-1)*nlon1+(iix);
	  src_add[2] = (jj)*nlon1+(ii-1);
	  src_add[3] = (jj)*nlon1+(iix);

	  /* Check to see if points are missing values */
	  for ( n = 0; n < 4; ++n )
	    if ( ! grid1_mask[src_add[n]] ) lfound = 0;
	}

      if ( lfound )
	{
	  double wgts[4];

	  wgts[0] = (x[i]-xm[ii])   * (y[i]-ym[jj])   / ((xm[ii-1]-xm[ii]) * (ym[jj-1]-ym[jj]));
	  wgts[1] = (x[i]-xm[ii-1]) * (y[i]-ym[jj])   / ((xm[ii]-xm[ii-1]) * (ym[jj-1]-ym[jj]));
	  wgts[2] = (x[i]-xm[ii])   * (y[i]-ym[jj-1]) / ((xm[ii-1]-xm[ii]) * (ym[jj]-ym[jj-1]));
	  wgts[3] = (x[i]-xm[ii-1]) * (y[i]-ym[jj-1]) / ((xm[ii]-xm[ii-1]) * (ym[jj]-ym[jj-1]));
	  
	  field[i] = 0;
	  for ( n = 0; n < 4; ++n )
	    field[i] += fieldm[src_add[n]] * wgts[n];
	}
    }
 
  if ( findex < gridsize2 ) progressStatus(0, 1, 1);

  if ( grid1_mask ) free(grid1_mask);
}

static
void restrict_boundbox(const double *restrict grid_bound_box, double *restrict bound_box)
{
  if ( bound_box[0] < grid_bound_box[0] && bound_box[1] > grid_bound_box[0] ) bound_box[0] = grid_bound_box[0];
  if ( bound_box[1] > grid_bound_box[1] && bound_box[0] < grid_bound_box[1] ) bound_box[1] = grid_bound_box[1];
  //  if ( bound_box[2] < grid_bound_box[2] && bound_box[3] > grid_bound_box[2] ) bound_box[2] = grid_bound_box[2];
  //  if ( bound_box[3] > grid_bound_box[3] && bound_box[2] < grid_bound_box[3] ) bound_box[3] = grid_bound_box[3];
}

static
void boundbox_from_corners(long ic, long nc, const double *restrict corner_lon,
			   const double *restrict corner_lat, double *restrict bound_box)
{
  long inc, j;
  double clon, clat;

    {
      inc = ic*nc;
      clat = corner_lat[inc];
      clon = corner_lon[inc];
      bound_box[0] = clat;
      bound_box[1] = clat;
      bound_box[2] = clon;
      bound_box[3] = clon;
      for ( j = 1; j < nc; ++j )
	{
	  clat = corner_lat[inc+j];
	  clon = corner_lon[inc+j];
	  if ( clat < bound_box[0] ) bound_box[0] = clat;
	  if ( clat > bound_box[1] ) bound_box[1] = clat;
	  if ( clon < bound_box[2] ) bound_box[2] = clon;
	  if ( clon > bound_box[3] ) bound_box[3] = clon;
	}
    }
}

#if defined(HAVE_LIBYAC)
#include "points.h"
#include "grid_reg2d.h"
#include "grid_search.h"
#include "bucket_search.h"
#include "event.h"
#include "search.h"
#include "clipping.h"
#endif

static
void intconarr2(double missval, int lon_is_circular,
		long nxm, long nym,  const double *restrict fieldm, const double *restrict xm, const double *restrict ym,
		long nc2, long gridsize2, double *field, const double *restrict x, const double *restrict y)
{
  long ndeps;
  int *deps;
  long i, ii = -1, jj = -1;
  long gridsize1;
  long nlon1 = nxm;
  double findex = 0;
  int *grid1_mask = NULL;

  printf(" nxm, nym %ld %ld\n", nxm, nym);
  //if ( lon_is_circular ) nlon1--;
  gridsize1 = (nxm-1)*(nym-1);

  deps = (int *) malloc(gridsize1*sizeof(int));

  grid1_mask = (int *) calloc(1, gridsize1*sizeof(int));
  for ( jj = 0; jj < nym-1; ++jj )
    for ( ii = 0; ii < nxm-1; ++ii )
      {
	if ( !DBL_IS_EQUAL(fieldm[jj*(nxm-1)+ii], missval) ) grid1_mask[jj*(nxm-1)+ii] = 1;
      }

  double grid1_bound_box[4];
  grid1_bound_box[0] = ym[0];
  grid1_bound_box[1] = ym[nym-1];
  if ( ym[0] > ym[nym-1] )
    {
      grid1_bound_box[0] = ym[nym-1];
      grid1_bound_box[1] = ym[0];
    }
  grid1_bound_box[2] = xm[0];
  grid1_bound_box[3] = xm[nxm-1];
 
  progressInit();

#if defined(HAVE_LIBYAC)
  enum edge_type quad_type[] = {GREAT_CIRCLE, GREAT_CIRCLE, GREAT_CIRCLE, GREAT_CIRCLE}; // not used !
  // enum edge_type quad_type[] = {LON_CIRCLE, LON_CIRCLE, LON_CIRCLE, LON_CIRCLE};

  int n;
  double weight_sum;

  double *weight;
  weight = (double *) malloc(gridsize1*sizeof(double));

  struct grid_cell *SourceCell;
  SourceCell = malloc (gridsize1  * sizeof(*SourceCell) );

  for ( int n = 0; n <  gridsize1; n++ ) {
    SourceCell[n].num_corners   = 4;
    SourceCell[n].edge_type     = quad_type;
    SourceCell[n].coordinates_x = malloc (4 * sizeof(SourceCell[n].coordinates_x[0]) );
    SourceCell[n].coordinates_y = malloc (4 * sizeof(SourceCell[n].coordinates_y[0]) );
  }

  struct grid_cell  TargetCell;

  TargetCell.num_corners   = nc2;
  TargetCell.edge_type     = quad_type;
  TargetCell.coordinates_x = malloc (nc2 * sizeof(*TargetCell.coordinates_x) );
  TargetCell.coordinates_y = malloc (nc2 * sizeof(*TargetCell.coordinates_y) );

  unsigned const * curr_deps;
  struct polygons polygons;

  polygon_create ( &polygons );
#endif

  /*
#if defined(_OPENMP)
#pragma omp parallel for default(none) \
  shared(ompNumThreads, field, fieldm, x, y, xm, ym, nxm, nym, gridsize2, missval, findex, nlon1, lon_is_circular, grid1_mask, nc2) \
  private(i, jj, ii)
#endif
  */
  for ( i = 0; i < gridsize2; ++i )
    {
      int src_add[4];                /*  address for the four source points    */
      long n;
      long iix;
      int lfound;
      int lprogress = 1;
      ndeps = 0;
      /*
#if defined(_OPENMP)
      if ( omp_get_thread_num() != 0 ) lprogress = 0;
#endif
      */
      field[i] = missval;
      
      // printf("%ld lonb: %g %g %g %g latb: %g %g %g %g\n", i+1, x[i*nc2]*RAD2DEG, x[i*nc2+1]*RAD2DEG, x[i*nc2+2]*RAD2DEG, x[i*nc2+3]*RAD2DEG, y[i*nc2]*RAD2DEG, y[i*nc2+1]*RAD2DEG, y[i*nc2+2]*RAD2DEG, y[i*nc2+3]*RAD2DEG);


      double bound_lon1, bound_lon2;
      double bound_box[4];
      boundbox_from_corners(i, nc2, x, y, bound_box);
      restrict_boundbox(grid1_bound_box, bound_box);
      bound_lon1 = bound_box[2];
      bound_lon2 = bound_box[3];
      //  printf("bound_box %ld  lon: %g %g lat: %g %g\n", i+1, bound_box[2]*RAD2DEG, bound_box[3]*RAD2DEG, bound_box[0]*RAD2DEG, bound_box[1]*RAD2DEG);
      /*
#if defined(_OPENMP)
#pragma omp atomic
#endif
      */
      findex++;
      if ( lprogress ) progressStatus(0, 1, findex/gridsize2);

      //      lfound = rect_grid_search(&ii, &jj, x[i], y[i], nxm, nym, xm, ym);
      //     for ( int k = 0; k < nxm; ++k ) printf("x: %d %g\n", k+1, xm[k]);
      //    for ( int k = 0; k < nym; ++k ) printf("y: %d %g\n", k+1, ym[k]*RAD2DEG);
      long imin = nxm, imax = -1, jmin = nym, jmax = -1;

      lfound = rect_grid_search2(&jmin, &jmax, bound_box[0], bound_box[1], nym, ym);
      bound_lon1 = bound_box[2];
      bound_lon2 = bound_box[3];
      if ( bound_lon1 <= grid1_bound_box[3] && bound_lon2 >= grid1_bound_box[2] )
	{
	  //printf("b1 %g %g\n", bound_lon1*RAD2DEG, bound_lon2*RAD2DEG);
	  if ( bound_lon1 < grid1_bound_box[2] && bound_lon2 > grid1_bound_box[2] ) bound_lon1 = grid1_bound_box[2];
	  if ( bound_lon2 > grid1_bound_box[3] && bound_lon1 < grid1_bound_box[3] ) bound_lon2 = grid1_bound_box[3];
	  lfound = rect_grid_search2(&imin, &imax, bound_lon1, bound_lon2, nxm, xm);
	  //printf("imin %ld  imax %ld  jmin %ld jmax %ld\n", imin, imax, jmin, jmax);
	  for ( long jm = jmin; jm <= jmax; ++jm )
	    for ( long im = imin; im <= imax; ++im )
	      deps[ndeps++] = jm*(nxm-1) + im;
	}


      bound_lon1 = bound_box[2];
      bound_lon2 = bound_box[3];
      if ( bound_lon1 <= grid1_bound_box[2] && bound_lon2 > grid1_bound_box[2] )
	{
	  bound_lon1 += 2*M_PI;
	  bound_lon2 += 2*M_PI;
	  //printf("b2 %g %g\n", bound_lon1*RAD2DEG, bound_lon2*RAD2DEG);
	  if ( bound_lon1 < grid1_bound_box[2] && bound_lon2 > grid1_bound_box[2] ) bound_lon1 = grid1_bound_box[2];
	  if ( bound_lon2 > grid1_bound_box[3] && bound_lon1 < grid1_bound_box[3] ) bound_lon2 = grid1_bound_box[3];
	  lfound = rect_grid_search2(&imin, &imax, bound_lon1, bound_lon2, nxm, xm);
	  //printf("imin %ld  imax %ld  jmin %ld jmax %ld\n", imin, imax, jmin, jmax);
	  for ( long jm = jmin; jm <= jmax; ++jm )
	    for ( long im = imin; im <= imax; ++im )
	      deps[ndeps++] = jm*(nxm-1) + im;
	}

      bound_lon1 = bound_box[2];
      bound_lon2 = bound_box[3];
      if ( bound_lon1 < grid1_bound_box[3] && bound_lon2 >= grid1_bound_box[3] )
	{
	  bound_lon1 -= 2*M_PI;
	  bound_lon2 -= 2*M_PI;
	  //printf("b3 %g %g\n", bound_lon1*RAD2DEG, bound_lon2*RAD2DEG);
	  if ( bound_lon1 < grid1_bound_box[2] && bound_lon2 > grid1_bound_box[2] ) bound_lon1 = grid1_bound_box[2];
	  if ( bound_lon2 > grid1_bound_box[3] && bound_lon1 < grid1_bound_box[3] ) bound_lon2 = grid1_bound_box[3];
	  lfound = rect_grid_search2(&imin, &imax, bound_lon1, bound_lon2, nxm, xm);
	  //printf("imin %ld  imax %ld  jmin %ld jmax %ld\n", imin, imax, jmin, jmax);
	  for ( long jm = jmin; jm <= jmax; ++jm )
	    for ( long im = imin; im <= imax; ++im )
	      deps[ndeps++] = jm*(nxm-1) + im;
	}

      //for ( long id = 0; id < ndeps; ++id )
	//	printf("dep %ld %d\n", id+1, deps[id]);
      /*
      if ( bound_lon1 < grid1_bound_box[2] && bound_box[3] >= grid1_bound_box[2] )
	lfound = rect_grid_search2(&imin, &imax, bound_box[2], bound_box[3], nxm, xm);
      */

#if defined(HAVE_LIBYAC)
      int index2 = i;
      /*
      int ilat2 = index2/nlonOut;
      int ilon2 = index2 - ilat2*nlonOut;
      */
      for ( int ic = 0; ic < nc2; ++ic )
	{
	  TargetCell.coordinates_x[ic] =  x[index2*nc2+ic];
	  TargetCell.coordinates_y[ic] =  y[index2*nc2+ic];
	}

      if ( cdoVerbose )
	{
	  printf("target:\n");
	  for ( int n = 0; n < nc2; ++n )
	    printf(" %g %g", TargetCell.coordinates_x[n]/DEG2RAD, TargetCell.coordinates_y[n]/DEG2RAD);
	  printf("\n");
	}
      /*
      if ( cdoVerbose )
	printf("num_deps_per_element %d %d\n", i, ndeps);
      */
      int num_deps = ndeps;
      int nSourceCells = num_deps;

      for ( int k = 0; k < num_deps; ++k )
	{
	  int index1 = deps[k];
	  int ilat1 = index1/(nxm-1);
	  int ilon1 = index1 - ilat1*(nxm-1);
	  /*
	  if ( cdoVerbose )
	    printf("  dep: %d %d %d %d %d %d\n", k, nlonOut, nlatOut, index1, ilon1, ilat1);
	  */
	  if ( ym[ilat1] < ym[ilat1+1] )
	    {
	      SourceCell[k].coordinates_x[0] =  xm[ilon1];
	      SourceCell[k].coordinates_y[0] =  ym[ilat1];
	      SourceCell[k].coordinates_x[1] =  xm[ilon1+1];
	      SourceCell[k].coordinates_y[1] =  ym[ilat1];
	      SourceCell[k].coordinates_x[2] =  xm[ilon1+1];
	      SourceCell[k].coordinates_y[2] =  ym[ilat1+1];
	      SourceCell[k].coordinates_x[3] =  xm[ilon1];
	      SourceCell[k].coordinates_y[3] =  ym[ilat1+1];
	    }
	  else
	    {
	      SourceCell[k].coordinates_x[0] =  xm[ilon1];
	      SourceCell[k].coordinates_y[0] =  ym[ilat1+1];
	      SourceCell[k].coordinates_x[1] =  xm[ilon1+1];
	      SourceCell[k].coordinates_y[1] =  ym[ilat1+1];
	      SourceCell[k].coordinates_x[2] =  xm[ilon1+1];
	      SourceCell[k].coordinates_y[2] =  ym[ilat1];
	      SourceCell[k].coordinates_x[3] =  xm[ilon1];
	      SourceCell[k].coordinates_y[3] =  ym[ilat1];
	    }
	  if ( cdoVerbose )
	    {
	      printf("source: %d\n", k);
	      for ( int n = 0; n < 4; ++n )
		printf(" %g %g", SourceCell[k].coordinates_x[n]/DEG2RAD, SourceCell[k].coordinates_y[n]/DEG2RAD);
	      printf("\n");
	    }
	}
      
      polygon_partial_weights(num_deps, SourceCell, TargetCell, weight, &polygons);

      correct_weights ( nSourceCells, weight );

      field[i] = missval;
      if ( num_deps ) field[i] = 0;
      for ( int k = 0; k < num_deps; ++k )
	{
	  int index1 = deps[k];
	  /*
	  int ilat1 = index1/(nxm-1);
	  int ilon1 = index1 - ilat1*(nxm-1);
	  long add1, add2;

	  add1 = index1;
	  add2 = index2;

	  yar_store_link_cnsrv(&remap.vars, add1, add2, weight[k]);
	  */
	  field[i] += fieldm[index1] * weight[k];
	  /*
	  if ( cdoVerbose )
	    printf("  result dep: %ld %d %d  %g\n", i, k, index1, weight[k]);
	  */
	}
#endif
    }
 
#if defined(HAVE_LIBYAC)
  polygon_destroy ( &polygons );
#endif

  if ( findex < gridsize2 ) progressStatus(0, 1, 1);

  if ( deps ) free(deps);
  if ( grid1_mask ) free(grid1_mask);
}


double intlin(double x, double y1, double x1, double y2, double x2)
{
  /*
    xlin - lineare interpolation

    Uwe Schulzweida  04/05/1995
  */
  double value;
  
  value = (y2*(x-x1)+y1*(x2-x)) / (x2-x1);

  return (value);
}


void intlinarr(long nxm, double *ym, double *xm, int nx, double *y, double *x)
{
  /*
    xlinarr - lineare interpolation over 1D array

    Uwe Schulzweida  04/05/1995
  */
  long j, jj;

  for ( jj = 1; jj < nxm; jj++ )
    for ( j = 0; j < nx; j++ )
      if ( x[j] >= xm[jj-1] && x[j] <= xm[jj] )
	y[j] = intlin(x[j], ym[jj-1], xm[jj-1], ym[jj], xm[jj]);
}


void intgridbil(field_t *field1, field_t *field2)
{
  int nlon1, nlat1;
  int nlon2, nlat2;
  int ilat;
  int gridID1, gridID2;
  int i, nmiss;
  int lon_is_circular;
  double *lon1, *lat1;
  double **array1_2D = NULL;
  double **field;
  double *array = NULL;
  double *array1, *array2;
  double missval;
  char units[CDI_MAX_NAME];
  /* static int index = 0; */

  gridID1 = field1->grid;
  gridID2 = field2->grid;
  array1  = field1->ptr;
  array2  = field2->ptr;
  missval = field1->missval;

  if ( ! (gridInqXvals(gridID1, NULL) && gridInqYvals(gridID1, NULL)) )
    cdoAbort("Source grid has no values");

  lon_is_circular = gridIsCircular(gridID1);

  nlon1 = gridInqXsize(gridID1);
  nlat1 = gridInqYsize(gridID1);

  array1_2D = (double **) malloc(nlat1*sizeof(double *));
  for ( ilat = 0; ilat < nlat1; ilat++ )
    array1_2D[ilat] = array1 + ilat*nlon1;

  if ( lon_is_circular ) nlon1 += 1;
  lon1 = (double *) malloc(nlon1*sizeof(double));
  lat1 = (double *) malloc(nlat1*sizeof(double));
  gridInqXvals(gridID1, lon1);
  gridInqYvals(gridID1, lat1);
  if ( lon_is_circular ) lon1[nlon1-1] = 0;

  gridInqXunits(gridID1, units);

  grid_to_radian(units, nlon1, lon1, "grid1 center lon"); 
  grid_to_radian(units, nlat1, lat1, "grid1 center lat"); 

  if ( lon_is_circular ) lon1[nlon1-1] = lon1[0] + 2*M_PI;

  nlon2 = gridInqXsize(gridID2);
  nlat2 = gridInqYsize(gridID2);

  if ( nlon2 == 1 && nlat2 == 1 )
    {
      double lon2, lat2;

      gridInqXvals(gridID2, &lon2);
      gridInqYvals(gridID2, &lat2);

      gridInqXunits(gridID2, units);

      grid_to_radian(units, nlon2, &lon2, "grid2 center lon"); 
      grid_to_radian(units, nlat2, &lat2, "grid2 center lat"); 

      if ( lon2 < lon1[0] ) lon2 += 2*M_PI;

      if ( lon2 > lon1[nlon1-1] )
	{
	  field  = array1_2D;
	  array1_2D = (double **) malloc(nlat1*sizeof(double *));
	  lon1 = (double *) realloc(lon1, (nlon1+1)*sizeof(double));
	  array = (double *) malloc(nlat1*(nlon1+1)*sizeof(double));

	  for ( ilat = 0; ilat < nlat1; ilat++ )
	    {
	      array1_2D[ilat] = array + ilat*(nlon1+1);  
	      memcpy(array1_2D[ilat], field[ilat], nlon1*sizeof(double));
	      array1_2D[ilat][nlon1] = array1_2D[ilat][0];
	      lon1[nlon1] = lon1[0] + 2*M_PI;
	    }
	  nlon1++;
	  free(field);
	}

      if ( lon2 < lon1[0] || lon2 > lon1[nlon1-1] )
	cdoAbort("Longitude %f out of bounds (%f to %f)!", lon2, lon1[0], lon1[nlon1-1]);

      if ( lat2 < MIN(lat1[0], lat1[nlat1-1]) ||
	   lat2 > MAX(lat1[0], lat1[nlat1-1]) )
	cdoAbort("Latitude %f out of bounds (%f to %f)!", lat2, lat1[0], lat1[nlat1-1]);

      *array2 = intlinarr2p(nlon1, nlat1, array1_2D, lon1, lat1, lon2, lat2);
      /*
      printf("%5d %f %f %f\n", index++, lon2, lat2, *array2);
      */
    }
  else
    {
      int gridsize2;
      double *lon2, *lat2;

      if ( gridInqType(gridID2) == GRID_GME ) gridID2 = gridToUnstructured(gridID2, 0);

      if ( gridInqType(gridID2) != GRID_UNSTRUCTURED && gridInqType(gridID2) != GRID_CURVILINEAR )
	gridID2 = gridToCurvilinear(gridID2, 0);

      if ( ! (gridInqXvals(gridID2, NULL) && gridInqYvals(gridID2, NULL)) )
	cdoAbort("Target grid has no values");

      gridsize2 = gridInqSize(gridID2);

      lon2 = (double *) malloc(gridsize2*sizeof(double));
      lat2 = (double *) malloc(gridsize2*sizeof(double));
      gridInqXvals(gridID2, lon2);
      gridInqYvals(gridID2, lat2);

      gridInqXunits(gridID2, units);

      grid_to_radian(units, gridsize2, lon2, "grid2 center lon"); 
      grid_to_radian(units, gridsize2, lat2, "grid2 center lat"); 

      for ( int i = 0; i < gridsize2; ++i )
	{
	  if ( lon2[i] < lon1[0]       ) lon2[i] += 2*M_PI;
	  if ( lon2[i] > lon1[nlon1-1] ) lon2[i] -= 2*M_PI;
	}

      intlinarr2(missval, lon_is_circular, 
		 nlon1, nlat1, array1, lon1, lat1,
		 gridsize2, array2, lon2, lat2);

      nmiss = 0;
      for ( i = 0; i < gridsize2; ++i )
	if ( DBL_IS_EQUAL(array2[i], missval) ) nmiss++;

      field2->nmiss = nmiss;

      free(lon2);
      free(lat2);
    }

  if (array) free(array);
  free(lon1);
  free(lat1);
  free(array1_2D);
}


void gridGenBounds1(int ny, double *yvals, double *ybounds)
{
  int i;

  for ( i = 0; i < ny-1; i++ )
    {
      ybounds[i+1] = 0.5*(yvals[i] + yvals[i+1]);
    }

  ybounds[0]  = 2*yvals[0] - ybounds[1];
  ybounds[ny] = 2*yvals[ny-1] - ybounds[ny-1];
}


void intgridcon(field_t *field1, field_t *field2)
{
  int nlon1, nlat1;
  int nlon1b, nlat1b;
  int nlon2, nlat2;
  int ilat;
  int gridID1, gridID2;
  int i, nmiss;
  int lon_is_circular;
  double *lon1, *lat1;
  double *lon1bounds, *lat1bounds;
  double **field;
  double *array = NULL;
  double *array1, *array2;
  double missval;
  char units[CDI_MAX_NAME];
  /* static int index = 0; */

  gridID1 = field1->grid;
  gridID2 = field2->grid;
  array1  = field1->ptr;
  array2  = field2->ptr;
  missval = field1->missval;

  if ( ! (gridInqXvals(gridID1, NULL) && gridInqYvals(gridID1, NULL)) )
    cdoAbort("Source grid has no values");

  lon_is_circular = gridIsCircular(gridID1);

  nlon1 = gridInqXsize(gridID1);
  nlat1 = gridInqYsize(gridID1);

  lon1 = (double *) malloc(nlon1*sizeof(double));
  lat1 = (double *) malloc(nlat1*sizeof(double));
  gridInqXvals(gridID1, lon1);
  gridInqYvals(gridID1, lat1);

  gridInqXunits(gridID1, units);

  grid_to_radian(units, nlon1, lon1, "grid1 center lon"); 
  grid_to_radian(units, nlat1, lat1, "grid1 center lat"); 

  nlon1b = nlon1 + 1;
  nlat1b = nlat1 + 1;
  lon1bounds = (double *) malloc(nlon1b*sizeof(double));
  lat1bounds = (double *) malloc(nlat1b*sizeof(double));

  gridGenBounds1(nlon1, lon1, lon1bounds);
  gridGenBounds1(nlat1, lat1, lat1bounds);

  for ( int i = 0; i < nlat1; ++i )
    printf("lat1 %d %g\n", i+1, lat1[i]*RAD2DEG);
  printf("lat1bounds: %g %g %g ... %g %g %g\n", lat1bounds[0]*RAD2DEG, lat1bounds[1]*RAD2DEG, lat1bounds[2]*RAD2DEG, lat1bounds[nlat1b-3]*RAD2DEG, lat1bounds[nlat1b-2]*RAD2DEG, lat1bounds[nlat1b-1]*RAD2DEG);
  printf("lon1bounds: %g %g %g ... %g %g %g\n", lon1bounds[0]*RAD2DEG, lon1bounds[1]*RAD2DEG, lon1bounds[2]*RAD2DEG, lon1bounds[nlon1b-3]*RAD2DEG, lon1bounds[nlon1b-2]*RAD2DEG, lon1bounds[nlon1b-1]*RAD2DEG);

  nlon2 = gridInqXsize(gridID2);
  nlat2 = gridInqYsize(gridID2);

  int gridsize2;

  if ( gridInqType(gridID2) == GRID_GME ) gridID2 = gridToUnstructured(gridID2, 0);

  if ( gridInqType(gridID2) != GRID_UNSTRUCTURED && gridInqType(gridID2) != GRID_CURVILINEAR )
    gridID2 = gridToCurvilinear(gridID2, 0);

  if ( ! (gridInqXvals(gridID2, NULL) && gridInqYvals(gridID2, NULL)) )
    cdoAbort("Target grid has no values");

  gridsize2 = gridInqSize(gridID2);

  int nc2;

  if ( gridInqType(gridID2) == GRID_UNSTRUCTURED )
    nc2 = gridInqNvertex(gridID2);
  else
    nc2 = 4;

  printf("nc2: %d\n", nc2);

  double *grid2_corner_lon = NULL, *grid2_corner_lat = NULL;

  if ( gridInqYbounds(gridID2, NULL) && gridInqXbounds(gridID2, NULL) )
    {
      grid2_corner_lon = (double *) malloc(nc2*gridsize2*sizeof(double));
      grid2_corner_lat = (double *) malloc(nc2*gridsize2*sizeof(double));
      gridInqXbounds(gridID2, grid2_corner_lon);
      gridInqYbounds(gridID2, grid2_corner_lat);
    }
  else
    {
      cdoAbort("grid2 corner missing!");
    }
 
  gridInqXunits(gridID2, units);

  grid_to_radian(units, nc2*gridsize2, grid2_corner_lon, "grid2 corner lon"); 
  grid_to_radian(units, nc2*gridsize2, grid2_corner_lat, "grid2 corner lat"); 
  /*
  for ( int i = 0; i < gridsize2; ++i )
    {
      if ( lon2[i] < lon1[0]       ) lon2[i] += 2*M_PI;
      if ( lon2[i] > lon1[nlon1-1] ) lon2[i] -= 2*M_PI;
    }
  */
  for ( i = 0; i < gridsize2; ++i ) array2[i] = missval;

  intconarr2(missval, lon_is_circular, 
	     nlon1b, nlat1b, array1, lon1bounds, lat1bounds,
	     nc2, gridsize2, array2, grid2_corner_lon, grid2_corner_lat);

  nmiss = 0;
  for ( i = 0; i < gridsize2; ++i )
    if ( DBL_IS_EQUAL(array2[i], missval) ) nmiss++;

  field2->nmiss = nmiss;

  if (grid2_corner_lon) free(grid2_corner_lon);
  if (grid2_corner_lat) free(grid2_corner_lat);

  if (array) free(array);
  free(lon1);
  free(lat1);
}


/* source code from pingo */
void interpolate(field_t *field1, field_t *field2)
{
  int i;
  double *lono_array, *lato_array, *lono, *lato;
  double *lon_array, *lat_array, *lon, *lat;
  //int gridsize_i
  int gridsize_o;
  int gridIDi;
  double *arrayIn;
  int gridIDo;
  double *arrayOut;
  double missval;
  int nmiss;
  long ilon, ilat, nxlon, nxlat, olon, olat;
  long l11, l12, l21, l22, l1, l2;
  double volon1, volon2, volat1, volat2;
  double *volon11, *volon12;
  double *volon21, *volon22;
  double vilon1, vilon2, vilat1, vilat2;
  double vlon1, vlon2, vlat1, vlat2;
  long *ilon11, *ilon12;
  long *ilon21, *ilon22;
  long *ilat1, *ilat2;
  long ilon1, ilon2;
  double sum, wsum;
  int k, n;
  double *xin_array, *xlon, *xlat;
  double **in0, **xin, **xout;
  int wrap_around, xlat_is_ascending;
  double a11, a12, a21, a22, b11, b12, b21, b22, t;
  double faclon1, faclon2, faclat1, faclat2;
  int nlon, nlat, out_nlon, out_nlat;

  gridIDi  = field1->grid;
  gridIDo  = field2->grid;
  arrayIn  = field1->ptr;
  arrayOut = field2->ptr;
  missval  = field1->missval;

  //gridsize_i = gridInqSize(gridIDi);
  gridsize_o = gridInqSize(gridIDo);

  nlon  = gridInqXsize(gridIDi);
  nlat  = gridInqYsize(gridIDi);
  out_nlon = gridInqXsize(gridIDo);
  out_nlat = gridInqYsize(gridIDo);

  lon_array = (double *) malloc((nlon + 2) * sizeof(double));
  lat_array = (double *) malloc((nlat + 2) * sizeof(double));
  lon = lon_array + 1;
  lat = lat_array + 1;

  if ( ! (gridInqXvals(gridIDi, NULL) && gridInqYvals(gridIDi, NULL)) )
    cdoAbort("Source grid has no values");

  if ( ! (gridInqXvals(gridIDo, NULL) && gridInqYvals(gridIDo, NULL)) )
    cdoAbort("Target grid has no values");

  gridInqXvals(gridIDi, lon);
  gridInqYvals(gridIDi, lat);

  /* Convert lat/lon units if required */
  {
    char units[CDI_MAX_NAME];
    gridInqXunits(gridIDi, units);
    grid_to_degree(units, nlon, lon, "grid1 center lon");
    gridInqYunits(gridIDi, units);
    grid_to_degree(units, nlat, lat, "grid1 center lat");
  }

  if ( nlon > 1 )
    {
      lon[-1] = lon[nlon - 1] - 360 > 2*lon[0] - lon[1] ?
	        lon[nlon - 1] - 360 : 2*lon[0] - lon[1];
      lon[nlon] = lon[0] + 360 < 2*lon[nlon-1] - lon[nlon-2] ?
 	          lon[0] + 360 : 2*lon[nlon-1] - lon[nlon-2];
    }
  else
    {
      lon[-1] = lon[0] - 360;
      lon[ 1] = lon[0] + 360;
    }

  if ( nlat > 1 )
    {
      lat[-1]   = 2*lat[0] - lat[1];
      lat[nlat] = 2*lat[nlat-1] - lat[nlat-2];
    }
  else
    {
      lat[-1] = lat[0] - 10;
      lat[ 1] = lat[nlat-1] + 10;
    }

  if ( lat[-1]   < -90 ) lat[-1] = -99;
  if ( lat[-1]   >  90 ) lat[-1] =  99;
  if ( lat[nlat] < -90 ) lat[nlat] = -99;
  if ( lat[nlat] >  90 ) lat[nlat] =  99;

  lono_array = (double *) malloc((out_nlon < 2 ? 4 : out_nlon + 2) * sizeof(double));
  lono = lono_array + 1;
  lato_array = (double *) malloc((out_nlat < 2 ? 4 : out_nlat + 2) * sizeof(double));
  lato = lato_array + 1;

  gridInqXvals(gridIDo, lono);
  gridInqYvals(gridIDo, lato);

  /* Convert lat/lon units if required */
  {
    char units[CDI_MAX_NAME];
    gridInqXunits(gridIDo, units);
    grid_to_degree(units, out_nlon, lono, "grid2 center lon");
    gridInqYunits(gridIDo, units);
    grid_to_degree(units, out_nlat, lato, "grid2 center lat");
  }

  for ( i = 0; i < out_nlon - 1; i++ )
    if (lono[i + 1] <= lono[i]) break;

  for ( i++; i < out_nlon; i++ )
    {
      lono[i] += 360;
      if ( i < out_nlon - 1 && lono[i + 1] + 360 <= lono[i] )
	cdoAbort("Longitudes of output grid are not in ascending order!");
    }

  if ( lono[out_nlon - 1] - lono[0] >= 360 )
    cdoAbort("The area covered by the longitudes of output grid must not overlap!");

  if ( lato[0] >  90.001 || lato[out_nlat - 1] >  90.001 ||
       lato[0] < -90.001 || lato[out_nlat - 1] < -90.001 )
    {
      cdoAbort("Latitudes of output grid must be between 90 and -90!");
    }

  for ( i = 0; i < out_nlat - 1; i++ )
    if ( IS_EQUAL(lato[i + 1], lato[i]) || (i < out_nlat - 2 &&
	((lato[i + 1] > lato[i]) != (lato[i + 2] > lato[i + 1]))) )
      {
	cdoAbort("Latitudes of output grid must be in descending or ascending order!");
      }

  if ( out_nlon > 1 )
    {
      lono[-1] = lono[out_nlon - 1] - 360 > 2 * lono[0] - lono[1] ?
	            lono[out_nlon - 1] - 360 : 2 * lono[0] - lono[1];
      lono[out_nlon] = lono[0] + 360 < 2 * lono[out_nlon - 1] - lono[out_nlon - 2] ?
	                  lono[0] + 360 : 2 * lono[out_nlon - 1] - lono[out_nlon - 2];
    }
  else
    {
      lono[-1] = lono[0] - 360;
      lono[ 1] = lono[0] + 360;
    }

  if ( out_nlat > 1 )
    {
      lato[-1]   = 2*lato[0] - lato[1];
      lato[out_nlat] = 2*lato[out_nlat-1] - lato[out_nlat-2];
    }
  else
    {
      lato[-1] = lato[0] - 10;
      lato[ 1] = lato[out_nlat-1] + 10;
    }

  if ( lato[-1]   < -90 ) lato[-1] = -99;
  if ( lato[-1]   >  90 ) lato[-1] =  99;
  if ( lato[out_nlat] < -90 ) lato[out_nlat] = -99;
  if ( lato[out_nlat] >  90 ) lato[out_nlat] =  99;

  nxlon = 2*nlon + 1;
  nxlat = 2*nlat + 1;
  xin_array = (double *) malloc(nxlon * nxlat * sizeof(double));
  xin = (double **) malloc(nxlat * sizeof(double *));

  for (ilat = 0; ilat < nxlat; ilat++)
    xin[ilat] = xin_array + ilat * nxlon;

  xlon = (double *) malloc(nxlon * sizeof (double));
  for ( ilon = 0; ilon < nlon; ilon++ )
    {
      xlon[2*ilon + 1] = lon[ilon];
      xlon[2*ilon] = (lon[ilon - 1] + lon[ilon]) / 2;
    }
  xlon[2 * nlon] = (lon[nlon - 1] + lon[nlon]) / 2;

  xlat = (double *) malloc((2 * nlat + 1) * sizeof (double));
  for ( ilat = 0; ilat < nlat; ilat++ )
    {
      xlat[2*ilat + 1] = lat[ilat];
      xlat[2*ilat] = (lat[ilat - 1] + lat[ilat]) / 2;
    }
  xlat[2 * nlat] = (lat[nlat - 1] + lat[nlat]) / 2;

  in0 = (double **) malloc(nlat * sizeof (double *));
  for (ilat = 0; ilat < nlat; ilat++)
    in0[ilat] = arrayIn + ilat * nlon;

  ilon11 = (long *) malloc(out_nlon * sizeof(long));
  ilon12 = (long *) malloc(out_nlon * sizeof(long));
  ilon21 = (long *) malloc(out_nlon * sizeof(long));
  ilon22 = (long *) malloc(out_nlon * sizeof(long));
  volon11 = (double *) malloc(out_nlon * sizeof(double));
  volon12 = (double *) malloc(out_nlon * sizeof(double));
  volon21 = (double *) malloc(out_nlon * sizeof(double));
  volon22 = (double *) malloc(out_nlon * sizeof(double));

  for (olon = 0; olon < out_nlon; olon++)
    {
      volon1 = (lono[olon - 1] + lono[olon]) / 2;
      volon2 = (lono[olon] + lono[olon + 1]) / 2;
      if ( IS_EQUAL(volon1, volon2) ) volon2 += 360;
      volon2 -= 360 * floor((volon1 - xlon[0]) / 360);
      volon1 -= 360 * floor((volon1 - xlon[0]) / 360);
      volon21[olon] = volon1;
      volon22[olon] = volon2;
      for (l21 = 0; l21 < nxlon && xlon[l21] < volon1; l21++);
      for (l22 = l21; l22 < nxlon && xlon[l22] < volon2; l22++);
      volon1 -= 360;
      volon2 -= 360;
      volon11[olon] = volon1;
      volon12[olon] = volon2;
      for (l11 = 0; xlon[l11] < volon1; l11++);
      for (l12 = l11; l12 < nxlon && xlon[l12] < volon2; l12++);
      ilon11[olon] = l11;
      ilon12[olon] = l12;
      ilon21[olon] = l21;
      ilon22[olon] = l22;
    }

  ilat1 = (long *) malloc(out_nlat * sizeof(long));
  ilat2 = (long *) malloc(out_nlat * sizeof(long));

  xlat_is_ascending = xlat[0] <= xlat[nxlat - 1];
  for ( olat = 0; olat < out_nlat; olat++ )
    {
      volat1 = (lato[olat - 1] + lato[olat]) / 2;
      volat2 = (lato[olat] + lato[olat + 1]) / 2;
      if (!xlat_is_ascending)
	{
	  if (volat1 > volat2)
	    {
	      for (l1 =  0; l1 < nxlat && xlat[l1] > volat1; l1++);
	      for (l2 = l1; l2 < nxlat && xlat[l2] > volat2; l2++);
	    }
	  else
	    {
	      for (l1 =  0; l1 < nxlat && xlat[l1] > volat2; l1++);
	      for (l2 = l1; l2 < nxlat && xlat[l2] > volat1; l2++);
	    }
	}
      else
	{
	  if (volat1 < volat2)
	    {
	      for (l1 =  0; l1 < nxlat && xlat[l1] < volat1; l1++);
	      for (l2 = l1; l2 < nxlat && xlat[l2] < volat2; l2++);
	    }
	  else
	    {
	      for (l1 =  0; l1 < nxlat && xlat[l1] < volat2; l1++);
	      for (l2 = l1; l2 < nxlat && xlat[l2] < volat1; l2++);
	    }
	}

      ilat1[olat] = l1;
      ilat2[olat] = l2;
    }

  xout = (double **) malloc(out_nlat * sizeof (double *));
  for (olat = 0; olat < out_nlat; olat++)
    xout[olat] = arrayOut + olat * out_nlon;

  wrap_around = nlon > 1 && (lon[nlon - 1] >= lon[-1] + 360 - 0.001
			      || lon[nlon] >= lon[ 0] + 360 - 0.001);

  for (ilat = 0; ilat < nlat; ilat++)
#if defined(SX)
#pragma vdir nodep
#endif
    for (ilon = 0; ilon < nlon; ilon++)
      xin[2 * ilat + 1][2 * ilon + 1] = in0[ilat][ilon];

  for (ilat = 0; ilat < nxlat; ilat += 2)
#if defined(SX)
#pragma vdir nodep
#endif
    for (ilon = 1; ilon < nxlon; ilon += 2)
      {
	sum = 0;
	n = 0;
	if (ilat > 0 && !DBL_IS_EQUAL(xin[ilat - 1][ilon], missval))
	  {
	    sum += xin[ilat - 1][ilon];
	    n++;
	  }
	if (ilat < nxlat - 1 && !DBL_IS_EQUAL(xin[ilat + 1][ilon], missval))
	  {
	    sum += xin[ilat + 1][ilon];
	    n++;
	  }
	xin[ilat][ilon] = n ? sum / n : missval;
      }

  for ( ilat = 1; ilat < nxlat; ilat += 2 )
#if defined(SX)
#pragma vdir nodep
#endif
    for ( ilon = 0; ilon < nxlon; ilon += 2 )
      {
	sum = 0;
	n = 0;
	if (ilon > 0 && !DBL_IS_EQUAL(xin[ilat][ilon - 1], missval))
	  {
	    sum += xin[ilat][ilon - 1];
	    n++;
	  }
	if (ilon == 0 && wrap_around && !DBL_IS_EQUAL(xin[ilat][2 * nlon - 1], missval))
	  {
	    sum += xin[ilat][2 * nlon - 1];
	    n++;
	  }
	if (ilon < nxlon - 1 && !DBL_IS_EQUAL(xin[ilat][ilon + 1], missval))
	  {
	    sum += xin[ilat][ilon + 1];
	    n++;
	  }
	if (ilon == nxlon - 1 && wrap_around && !DBL_IS_EQUAL(xin[ilat][1], missval))
	  {
	    sum += xin[ilat][1];
	    n++;
	  }
	xin[ilat][ilon] = n ? sum / n : missval;
      }

  for ( ilat = 0; ilat < nxlat; ilat += 2 )
#if defined(SX)
#pragma vdir nodep
#endif
    for ( ilon = 0; ilon < nxlon; ilon += 2 )
      {
	sum = 0;
	n = 0;
	if (ilon > 0 && !DBL_IS_EQUAL(xin[ilat][ilon - 1], missval))
	  {
	    sum += xin[ilat][ilon - 1];
	    n++;
	  }
	if (ilon == 0 && wrap_around && !DBL_IS_EQUAL(xin[ilat][2 * nlon - 1], missval))
	  {
	    sum += xin[ilat][2 * nlon - 1];
	    n++;
	  }
	if (ilon < nxlon - 1 && !DBL_IS_EQUAL(xin[ilat][ilon + 1], missval))
	  {
	    sum += xin[ilat][ilon + 1];
	    n++;
	  }
	if (ilon == nxlon - 1 && wrap_around && !DBL_IS_EQUAL(xin[ilat][1], missval))
	  {
	    sum += xin[ilat][1];
	    n++;
	  }
	if (ilat > 0 && !DBL_IS_EQUAL(xin[ilat - 1][ilon], missval))
	  {
	    sum += xin[ilat - 1][ilon];
	    n++;
	  }
	if (ilat < nxlat - 1 && !DBL_IS_EQUAL(xin[ilat + 1][ilon], missval))
	  {
	    sum += xin[ilat + 1][ilon];
	    n++;
	  }
	xin[ilat][ilon] = n ? sum / n : missval;
      }

  for ( olat = 0; olat < out_nlat; olat++ )
    {
      if ( lato[-1] < lato[out_nlat] )
	{
	  volat1 = (lato[olat - 1] + lato[olat]) / 2;
	  volat2 = (lato[olat] + lato[olat + 1]) / 2;
	}
      else
	{
	  volat2 = (lato[olat - 1] + lato[olat]) / 2;
	  volat1 = (lato[olat] + lato[olat + 1]) / 2;
	}

      for ( olon = 0; olon < out_nlon; olon++ )
	{
	  sum = 0;
	  wsum = 0;
	  for (k = 0; k < 2; k++)
	    {
	      if (k == 0)
		{
		  ilon1 = ilon11[olon];
		  ilon2 = ilon12[olon];
		  volon1 = volon11[olon];
		  volon2 = volon12[olon];
		}
	      else
		{
		  ilon1 = ilon21[olon];
		  ilon2 = ilon22[olon];
		  volon1 = volon21[olon];
		  volon2 = volon22[olon];
		}

	      for ( ilon = ilon1; ilon <= ilon2; ilon++ )
		{
		  if ( ilon == 0 || ilon == nxlon ) continue;
		  vilon1 = xlon[ilon - 1];
		  vilon2 = xlon[ilon];
		  for ( ilat = ilat1[olat]; ilat <= ilat2[olat]; ilat++ )
		    {
		      if ( ilat == 0 || ilat == nxlat ) continue;
		      if ( xlat_is_ascending )
			{
			  vilat1 = xlat[ilat - 1];
			  vilat2 = xlat[ilat];
			  a11 = xin[ilat - 1][ilon - 1];
			  a12 = xin[ilat - 1][ilon];
			  a21 = xin[ilat][ilon - 1];
			  a22 = xin[ilat][ilon];
			}
		      else
			{
			  vilat1 = xlat[ilat];
			  vilat2 = xlat[ilat - 1];
			  a11 = xin[ilat][ilon - 1];
			  a12 = xin[ilat][ilon];
			  a21 = xin[ilat - 1][ilon - 1];
			  a22 = xin[ilat - 1][ilon];
			}
		      if ( DBL_IS_EQUAL(a11, missval) || DBL_IS_EQUAL(a12, missval) ||
			   DBL_IS_EQUAL(a21, missval) || DBL_IS_EQUAL(a22, missval) )
			{
			  continue;
			}
		      if ( volon1 <= vilon1 && vilon2 <= volon2 &&
			   volat1 <= vilat1 && vilat2 <= volat2 )
			{
			  vlon1 = vilon1 * M_PI / 180;
			  vlon2 = vilon2 * M_PI / 180;
			  vlat1 = vilat1 * M_PI / 180;
			  vlat2 = vilat2 * M_PI / 180;
			  b11 = a11;
			  b12 = a12;
			  b21 = a21;
			  b22 = a22;
			}
		      else
			{
			  vlon1 = (volon1 <= vilon1 ? vilon1 : volon1);
			  vlon2 = (vilon2 <= volon2 ? vilon2 : volon2);
			  vlat1 = (volat1 <= vilat1 ? vilat1 : volat1);
			  vlat2 = (vilat2 <= volat2 ? vilat2 : volat2);
			  if ( vlon1 >= vlon2 - (volon2 - volon1) * 1e-5 ||
			       vlat1 >= vlat2 - (volat2 - volat1) * 1e-5)
			    {
			      continue;
			    }
			  faclon1 = (vlon1 - vilon1) / (vilon2 - vilon1);
			  faclon2 = (vlon2 - vilon1) / (vilon2 - vilon1);
			  faclat1 = (vlat1 - vilat1) / (vilat2 - vilat1);
			  faclat2 = (vlat2 - vilat1) / (vilat2 - vilat1);
			  vlon1 *= M_PI / 180;
			  vlon2 *= M_PI / 180;
			  vlat1 *= M_PI / 180;
			  vlat2 *= M_PI / 180;
			  b11 = a11 + (a12 - a11)*faclon1 + (a21 - a11)*faclat1
			      + (a22 - a12 - a21 + a11)*faclon1*faclat1;
			  b12 = a11 + (a12 - a11)*faclon2 + (a21 - a11)*faclat1
			      + (a22 - a12 - a21 + a11)*faclon2*faclat1;
			  b21 = a11 + (a12 - a11)*faclon1 + (a21 - a11)*faclat2
			      + (a22 - a12 - a21 + a11)*faclon1*faclat2;
			  b22 = a11 + (a12 - a11)*faclon2 + (a21 - a11)*faclat2
			      + (a22 - a12 - a21 + a11)*faclon2*faclat2;
			}
		      wsum += (vlon2 - vlon1) * (sin(vlat2) - sin(vlat1));
		      t = 2 * sin((vlat2 + vlat1) / 2) *
		  	      sin((vlat2 - vlat1) / 2) / (vlat2 - vlat1);
		      sum += (vlon2 - vlon1) / 2 * ((b11 + b12) * (t - sin(vlat1)) +
				                    (b21 + b22) * (sin(vlat2) - t));
		    }
		}
	    }
	  xout[olat][olon] = IS_NOT_EQUAL(wsum, 0) ? sum / wsum : missval;
	}
    }

  nmiss = 0;
  for ( i = 0; i < gridsize_o; i++ )
    if ( DBL_IS_EQUAL(arrayOut[i], missval) ) nmiss++;

  field2->nmiss = nmiss;

  free(lon_array);
  free(lat_array);
  free(lono_array);
  free(lato_array);
  free(xin);
  free(xin_array);
  free(xlon);
  free(xlat);
  free(in0);
  free(ilon11);
  free(ilon12);
  free(ilon21);
  free(ilon22);
  free(volon11);
  free(volon12);
  free(volon21);
  free(volon22);
  free(ilat1);
  free(ilat2);
  free(xout);
}


/* source code from pingo */
void contrast(void)
{
  int rec = 1;
  int nlat, nlon;
  int i, j, size = 0;
  double missval;
  double **work;
  double **in;
  double **out;
  double *lon;
  double *lat;

  static double *xin_array, **xin, **xout, **xwork[17];
  static double **r, **r_bar, **r_new, **r_bar_new;
  static double **p, **p_bar, **p_new, **p_bar_new, **swap;
  static double a0, a1, a2, a3, a4, a5, a6, a7, a8;
  static double dlon0, dlon1, dslat0, dslat1;
  static double w00, w01, w10, w11, wsum;
  static double lon0, lon1, lon2, lat0, lat1, lat2;
  static double flat00, flat01, flat10, flat11;
  static long ilon, ilat;
  static int determine_matrix, wrap_around, stop_iteration;
  static double table[2][2][2][4]
     = { {{{8 / 32., 8 / 32., 8 / 32., 8 / 32.},
	  {12 / 32., 8 / 32., 0, 12 / 32.}},
	 {{12 / 32., 0, 8 / 32., 12 / 32.},
	  {16 / 32., 0, 0, 16 / 32.}}},
	 {{{0, 12 / 32., 12 / 32., 8 / 32.},
	   {0, 16 / 32., 0, 16 / 32.}},
	  {{0, 0, 16 / 32., 16 / 32.},
	   {0, 0, 0, 32 / 32.}}}
     };
  static double *case_table;
  static double f;
  static double nom, denom, a, b;
  static const double eps = 1e-20;
  static double max;
  static int iter;
  static float iter_sum = 0, iter_n = 0;

  nlat = 0;
  nlon = 0;
  missval = 0;
  work = 0;
  in = 0;
  out = 0;
  lon = 0;
  lat = 0;

  if (rec == 1)
    {
      xin_array = (double *) malloc((nlat + 2) * (nlon + 2) * sizeof(double));
      xin = (double **) malloc((nlat + 2) * sizeof(double *));
      *xin = *(xin + 1);
      for (ilat = -1; ilat <= nlat; ilat++)
	xin[ilat] = xin_array + (ilat + 1) * (nlon + 2) + 1;
      xout = (double **) malloc(nlat * sizeof(double *));
      for (ilat = 0; ilat < nlat; ilat++)
	xout[ilat] = out[0] + ilat * nlon;
      for (j = 0; j < 17; j++)
	{
	  xwork[j] = (double **) malloc(nlat * sizeof(double *));
	  for (ilat = 0; ilat < nlat; ilat++)
	    xwork[j][ilat] = work[j] + ilat * nlon;
	}
      wrap_around = nlon > 1 && (lon[nlon - 1] >= lon[-1] + 360 - 0.001
				 || lon[nlon] >= lon[0] + 360 - 0.001);
      determine_matrix = TRUE;
    }
  else
    {
      determine_matrix = FALSE;
      for (i = 0; i < size; i++)
	if ( DBL_IS_EQUAL(in[0][i], missval) != DBL_IS_EQUAL(out[0][i], missval) )
	  {
	    determine_matrix = TRUE;
	    break;
	  }
    }
  for (ilon = 0; ilon < nlon; ilon++)
    {
      for (ilat = 0; ilat < nlat; ilat++)
	xin[ilat][ilon] = in[0][ilon + ilat * nlon];
      xin[-1][ilon] = xin[nlat][ilon] = missval;
    }
  if (wrap_around)
    for (ilat = -1; ilat <= nlat; ilat++)
      {
	xin[ilat][-1] = xin[ilat][nlon - 1];
	xin[ilat][nlon] = xin[ilat][0];
      }
  else
    for (ilat = -1; ilat <= nlat; ilat++)
      xin[ilat][-1] = xin[ilat][nlon] = missval;

  if (determine_matrix)
    {
      for (ilon = 0; ilon < nlon; ilon++)
	{
	  lon1 = lon[ilon];
	  lon0 = (lon[ilon - 1] + lon1) / 2;
	  lon2 = (lon[ilon + 1] + lon1) / 2;
	  dlon0 = lon1 - lon0;
	  dlon1 = lon2 - lon1;
	  for (ilat = 0; ilat < nlat; ilat++)
	    {
	      lat1 = lat[ilat] * M_PI / 180;
	      lat0 = (lat[ilat - 1] * M_PI / 180 + lat1) / 2;
	      lat2 = (lat[ilat + 1] * M_PI / 180 + lat1) / 2;
	      dslat0 = sin (lat1) - sin (lat0);
	      dslat1 = sin (lat2) - sin (lat1);
	      flat00 = 2 / (lat1 - lat0) * sin ((lat1 + lat0) / 2) * 
		       sin ((lat1 - lat0) /2) - sin (lat0);
	      flat01 = dslat0 - flat00;
	      flat10 = 2 / (lat2 - lat1) * sin ((lat2 + lat1) / 2) * 
                       sin ((lat2 - lat1) / 2) - sin (lat1);
	      flat11 = dslat1 - flat10;
	      flat00 /= 2;
	      flat01 /= 2;
	      flat10 /= 2;
	      flat11 /= 2;
	      if ( DBL_IS_EQUAL(xin[ilat][ilon], missval) )
		{
		  xwork[4][ilat][ilon] = 1;
		  xwork[0][ilat][ilon] = xwork[1][ilat][ilon]
		    = xwork[2][ilat][ilon] = xwork[3][ilat][ilon]
		    = xwork[5][ilat][ilon] = xwork[6][ilat][ilon]
		    = xwork[7][ilat][ilon] = xwork[8][ilat][ilon] = 0;
		}
	      else
		{
		  w00 = dslat0 * dlon0;
		  w01 = dslat0 * dlon1;
		  w10 = dslat1 * dlon0;
		  w11 = dslat1 * dlon1;
		  wsum = w00 + w01 + w10 + w11;

		  a4 = dlon0 * flat01;
		  if ( DBL_IS_EQUAL(xin[ilat - 1][ilon], missval) )
		    {
		      a1 = 0;
		      a4 += dlon0 * flat00;
		    }
		  else
		    {
		      a1 = dlon0 * flat00 / 2;
		      a4 += a1;
		    }
		  if ( DBL_IS_EQUAL(xin[ilat][ilon - 1], missval) )
		    {
		      a3 = 0;
		      a4 += dlon0 * flat01;
		    }
		  else
		    {
		      a3 = dlon0 * flat01 / 2;
		      a4 += a3;
		    }
		  case_table = table[DBL_IS_EQUAL(xin[ilat - 1][ilon - 1], missval)]
		                    [DBL_IS_EQUAL(xin[ilat - 1][ilon], missval)]
		                    [DBL_IS_EQUAL(xin[ilat][ilon - 1], missval)];
		  f = dlon0 * flat00;
		  a0 = case_table[0] * f;
		  a1 += case_table[1] * f;
		  a3 += case_table[2] * f;
		  a4 += case_table[3] * f;
		  xwork[0][ilat][ilon] = a0;
		  xwork[1][ilat][ilon] = a1;
		  xwork[3][ilat][ilon] = a3;
		  xwork[4][ilat][ilon] = a4;

		  a4 = dlon1 * flat01;
		  if ( DBL_IS_EQUAL(xin[ilat - 1][ilon], missval) )
		    {
		      a1 = 0;
		      a4 += dlon1 * flat00;
		    }
		  else
		    {
		      a1 = dlon1 * flat00 / 2;
		      a4 += a1;
		    }

		  if ( DBL_IS_EQUAL(xin[ilat][ilon + 1], missval) )
		    {
		      a5 = 0;
		      a4 += dlon1 * flat01;
		    }
		  else
		    {
		      a5 = dlon1 * flat01 / 2;
		      a4 += a5;
		    }
		  case_table = table[DBL_IS_EQUAL(xin[ilat - 1][ilon + 1], missval)]
		                    [DBL_IS_EQUAL(xin[ilat - 1][ilon], missval)]
		                    [DBL_IS_EQUAL(xin[ilat][ilon + 1], missval)];
		  f = dlon1 * flat00;
		  a2 = case_table[0] * f;
		  a1 += case_table[1] * f;
		  a5 += case_table[2] * f;
		  a4 += case_table[3] * f;
		  xwork[2][ilat][ilon] += a2;
		  xwork[1][ilat][ilon] += a1;
		  xwork[5][ilat][ilon] += a5;
		  xwork[4][ilat][ilon] += a4;

		  a4 = dlon0 * flat10;
		  if ( DBL_IS_EQUAL(xin[ilat + 1][ilon], missval) )
		    {
		      a7 = 0;
		      a4 += dlon0 * flat11;
		    }
		  else
		    {
		      a7 = dlon0 * flat11 / 2;
		      a4 += a7;
		    }

		  if ( DBL_IS_EQUAL(xin[ilat][ilon - 1], missval))
		    {
		      a3 = 0;
		      a4 += dlon0 * flat10;
		    }
		  else
		    {
		      a3 = dlon0 * flat10 / 2;
		      a4 += a3;
		    }

		  case_table = table[DBL_IS_EQUAL(xin[ilat + 1][ilon - 1], missval)]
		                    [DBL_IS_EQUAL(xin[ilat + 1][ilon], missval)]
		                    [DBL_IS_EQUAL(xin[ilat][ilon - 1], missval)];
		  f = dlon0 * flat11;
		  a6 = case_table[0] * f;
		  a7 += case_table[1] * f;
		  a3 += case_table[2] * f;
		  a4 += case_table[3] * f;
		  xwork[6][ilat][ilon] += a6;
		  xwork[7][ilat][ilon] += a7;
		  xwork[3][ilat][ilon] += a3;
		  xwork[4][ilat][ilon] += a4;

		  a4 = dlon1 * flat10;
		  if ( DBL_IS_EQUAL(xin[ilat + 1][ilon], missval) )
		    {
		      a7 = 0;
		      a4 += dlon1 * flat11;
		    }
		  else
		    {
		      a7 = dlon1 * flat11 / 2;
		      a4 += a7;
		    }

		  if ( DBL_IS_EQUAL(xin[ilat][ilon + 1], missval) )
		    {
		      a5 = 0;
		      a4 += dlon1 * flat10;
		    }
		  else
		    {
		      a5 = dlon1 * flat10 / 2;
		      a4 += a5;
		    }

		  case_table = table[DBL_IS_EQUAL(xin[ilat + 1][ilon + 1], missval)]
		                    [DBL_IS_EQUAL(xin[ilat + 1][ilon], missval)]
		                    [DBL_IS_EQUAL(xin[ilat][ilon + 1], missval)];
		  f = dlon1 * flat11;
		  a8 = case_table[0] * f;
		  a7 += case_table[1] * f;
		  a5 += case_table[2] * f;
		  a4 += case_table[3] * f;
		  xwork[8][ilat][ilon] += a8;
		  xwork[7][ilat][ilon] += a7;
		  xwork[5][ilat][ilon] += a5;
		  xwork[4][ilat][ilon] += a4;

		  xwork[0][ilat][ilon] /= wsum;
		  xwork[1][ilat][ilon] /= wsum;
		  xwork[2][ilat][ilon] /= wsum;
		  xwork[3][ilat][ilon] /= wsum;
		  xwork[4][ilat][ilon] /= wsum;
		  xwork[5][ilat][ilon] /= wsum;
		  xwork[6][ilat][ilon] /= wsum;
		  xwork[7][ilat][ilon] /= wsum;
		  xwork[8][ilat][ilon] /= wsum;
		}
	    }
	}
    }

  /* Solve sparse linear equation system
     xin[ilat][ilon] = xwork[0][ilat][ilon]*xout[ilat-1][ilon-1] 
                     + xwork[1][ilat][ilon]*xout[ilat-1][ilon  ] 
	             + xwork[2][ilat][ilon]*xout[ilat-1][ilon+1] 
	             + xwork[3][ilat][ilon]*xout[ilat  ][ilon-1] 
	             + xwork[4][ilat][ilon]*xout[ilat  ][ilon  ] 
	             + xwork[5][ilat][ilon]*xout[ilat  ][ilon+1] 
	             + xwork[6][ilat][ilon]*xout[ilat+1][ilon-1] 
	             + xwork[7][ilat][ilon]*xout[ilat+1][ilon  ] 
	             + xwork[8][ilat][ilon]*xout[ilat+1][ilon+1]
     using the biconjugate gradient method */

  max = 0;
  for (ilat = 0; ilat < nlat; ilat++)
    for (ilon = 0; ilon < nlon; ilon++)
      {
	f = xin[ilat][ilon];
	if (!DBL_IS_EQUAL(f, missval) && f > max)
	  max = f;
      }

  r = xwork[9];
  r_bar = xwork[10];
  r_new = xwork[11];
  r_bar_new = xwork[12];
  p = xwork[13];
  p_bar = xwork[14];
  p_new = xwork[15];
  p_bar_new = xwork[16];

  for (ilat = 0; ilat < nlat; ilat++)
    for (ilon = 0; ilon < nlon; ilon++)
      xout[ilat][ilon] = xin[ilat][ilon];

  for (ilat = 0; ilat < nlat; ilat++)
    for (ilon = 0; ilon < nlon; ilon++)
      r[ilat][ilon] = r_bar[ilat][ilon]
	            = p[ilat][ilon]
	            = p_bar[ilat][ilon]
	            = xin[ilat][ilon] - (xwork[0][ilat][ilon] * xin[ilat - 1][ilon - 1]
	                              + xwork[1][ilat][ilon] * xin[ilat - 1][ilon]
	                              + xwork[2][ilat][ilon] * xin[ilat - 1][ilon + 1]
	                              + xwork[3][ilat][ilon] * xin[ilat][ilon - 1]
	                              + xwork[4][ilat][ilon] * xin[ilat][ilon]
	                              + xwork[5][ilat][ilon] * xin[ilat][ilon + 1]
	                              + xwork[6][ilat][ilon] * xin[ilat + 1][ilon - 1]
	                              + xwork[7][ilat][ilon] * xin[ilat + 1][ilon]
	                              + xwork[8][ilat][ilon] * xin[ilat + 1][ilon + 1]);

  for (iter = 1;; iter++)
    {
      stop_iteration = TRUE;
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  if (fabs (r[ilat][ilon]) > eps * max)
	    {
	      stop_iteration = FALSE;
	      break;
	    }
      if (stop_iteration)
	break;
      /*
      if (user_asked)
	{
	  lock ();
	  fprintf (stderr,
		   "%s: Status: Raising contrast of record %d"
		   " iteration step %d", prompt, rec, iter);
	  if (iter_n)
	    fprintf (stderr, " of approximately %d.\n",
		     (int) (iter_sum / iter_n));
	  else
	    fputs (".\n", stderr);
	  fflush (stderr);
	  unlock ();
	  user_asked = FALSE;
	}
      */
      if (iter == 1)
	{
	  nom = 0;
	  for (ilat = 0; ilat < nlat; ilat++)
	    for (ilon = 0; ilon < nlon; ilon++)
	      nom += r[ilat][ilon] * r_bar[ilat][ilon];
	}
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_new[ilat][ilon] = xwork[4][ilat][ilon] * p[ilat][ilon];
      for (ilat = 1; ilat < nlat; ilat++)
	{
	  for (ilon = 1; ilon < nlon; ilon++)
	    r_new[ilat][ilon] +=
	      xwork[0][ilat][ilon] * p[ilat - 1][ilon - 1];
	  r_new[ilat][0] += xwork[0][ilat][0] * p[ilat - 1][nlon - 1];
	}
      for (ilat = 1; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_new[ilat][ilon] += xwork[1][ilat][ilon] * p[ilat - 1][ilon];
      for (ilat = 1; ilat < nlat; ilat++)
	{
	  for (ilon = 0; ilon < nlon - 1; ilon++)
	    r_new[ilat][ilon] +=
	      xwork[2][ilat][ilon] * p[ilat - 1][ilon + 1];
	  r_new[ilat][nlon - 1] +=
	    xwork[2][ilat][nlon - 1] * p[ilat - 1][0];
	}
      for (ilat = 0; ilat < nlat; ilat++)
	{
	  for (ilon = 1; ilon < nlon; ilon++)
	    r_new[ilat][ilon] += xwork[3][ilat][ilon] * p[ilat][ilon - 1];
	  r_new[ilat][0] += xwork[3][ilat][0] * p[ilat][nlon - 1];
	}
      for (ilat = 0; ilat < nlat; ilat++)
	{
	  for (ilon = 0; ilon < nlon - 1; ilon++)
	    r_new[ilat][ilon] +=
	      xwork[5][ilat][ilon] * p[ilat][ilon + 1];
	  r_new[ilat][nlon - 1] +=
	    xwork[5][ilat][nlon - 1] * p[ilat][0];
	}
      for (ilat = 0; ilat < nlat - 1; ilat++)
	{
	  for (ilon = 1; ilon < nlon; ilon++)
	    r_new[ilat][ilon] +=
	      xwork[6][ilat][ilon] * p[ilat + 1][ilon - 1];
	  r_new[ilat][0] += xwork[6][ilat][0] * p[ilat + 1][nlon - 1];
	}
      for (ilat = 0; ilat < nlat - 1; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_new[ilat][ilon] += xwork[7][ilat][ilon] * p[ilat + 1][ilon];
      for (ilat = 0; ilat < nlat - 1; ilat++)
	{
	  for (ilon = 0; ilon < nlon - 1; ilon++)
	    r_new[ilat][ilon] +=
	      xwork[8][ilat][ilon] * p[ilat + 1][ilon + 1];
	  r_new[ilat][nlon - 1] +=
	    xwork[8][ilat][nlon - 1] * p[ilat + 1][0];
	}
      denom = 0;
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  denom += p_bar[ilat][ilon] * r_new[ilat][ilon];

      if ( IS_EQUAL(denom, 0) ) break;

      a = nom / denom;

      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_new[ilat][ilon] = r[ilat][ilon] - a * r_new[ilat][ilon];
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_bar_new[ilat][ilon] =
	    xwork[4][ilat][ilon] * p_bar[ilat][ilon];
      for (ilat = 1; ilat < nlat; ilat++)
	{
	  for (ilon = 1; ilon < nlon; ilon++)
	    r_bar_new[ilat][ilon] += xwork[8][ilat - 1][ilon - 1] * p_bar[ilat - 1][ilon - 1];

	  r_bar_new[ilat][0] += xwork[8][ilat - 1][nlon - 1] * p_bar[ilat - 1][nlon - 1];
	}

      for (ilat = 1; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_bar_new[ilat][ilon] += xwork[7][ilat - 1][ilon] * p_bar[ilat - 1][ilon];

      for (ilat = 1; ilat < nlat; ilat++)
	{
	  for (ilon = 0; ilon < nlon - 1; ilon++)
	    r_bar_new[ilat][ilon] += xwork[6][ilat - 1][ilon + 1] * p_bar[ilat - 1][ilon + 1];

	  r_bar_new[ilat][nlon - 1] += xwork[6][ilat - 1][0] * p_bar[ilat - 1][0];
	}
      for (ilat = 0; ilat < nlat; ilat++)
	{
	  for (ilon = 1; ilon < nlon; ilon++)
	    r_bar_new[ilat][ilon] += xwork[5][ilat][ilon - 1] * p_bar[ilat][ilon - 1];
	  r_bar_new[ilat][0] += xwork[5][ilat][nlon - 1] * p_bar[ilat][nlon - 1];
	}

      for (ilat = 0; ilat < nlat; ilat++)
	{
	  for (ilon = 0; ilon < nlon - 1; ilon++)
	    r_bar_new[ilat][ilon] += xwork[3][ilat][ilon + 1] * p_bar[ilat][ilon + 1];

	  r_bar_new[ilat][nlon - 1] += xwork[3][ilat][0] * p_bar[ilat][0];
	}
      for (ilat = 0; ilat < nlat - 1; ilat++)
	{
	  for (ilon = 1; ilon < nlon; ilon++)
	    r_bar_new[ilat][ilon] += xwork[2][ilat + 1][ilon - 1] * p_bar[ilat + 1][ilon - 1];
	  r_bar_new[ilat][0] += xwork[2][ilat + 1][nlon - 1] * p_bar[ilat + 1][nlon - 1];
	}
      for (ilat = 0; ilat < nlat - 1; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_bar_new[ilat][ilon] += xwork[1][ilat + 1][ilon] * p_bar[ilat + 1][ilon];
      for (ilat = 0; ilat < nlat - 1; ilat++)
	{
	  for (ilon = 0; ilon < nlon - 1; ilon++)
	    r_bar_new[ilat][ilon] += xwork[0][ilat + 1][ilon + 1] * p_bar[ilat + 1][ilon + 1];
	  r_bar_new[ilat][nlon - 1] += xwork[0][ilat + 1][0] * p_bar[ilat + 1][0];
	}
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  r_bar_new[ilat][ilon] = r_bar[ilat][ilon] - a * r_bar_new[ilat][ilon];
      denom = nom;
      nom = 0;
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  nom += r_bar_new[ilat][ilon] * r_new[ilat][ilon];
      if ( IS_EQUAL(denom, 0) )
	break;
      b = nom / denom;
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  {
	    p_new[ilat][ilon] = r_new[ilat][ilon] + b * p[ilat][ilon];
	    p_bar_new[ilat][ilon] = r_bar_new[ilat][ilon] + b * p_bar[ilat][ilon];
	  }
      for (ilat = 0; ilat < nlat; ilat++)
	for (ilon = 0; ilon < nlon; ilon++)
	  if ( !DBL_IS_EQUAL(xout[ilat][ilon], missval) )
	    xout[ilat][ilon] += a * p[ilat][ilon];
      swap = r_new;
      r_new = r;
      r = swap;
      swap = r_bar_new;
      r_bar_new = r_bar;
      r_bar = swap;
      swap = p_new;
      p_new = p;
      p = swap;
      swap = p_bar_new;
      p_bar_new = p_bar;
      p_bar = swap;
    }
  iter_sum = iter_sum * 0.9 + iter;
  iter_n = iter_n * 0.9 + 1;

  free(xin_array);
  free(xin);
  free(xout);
  for (j = 0; j < 17; j++)
    free(xwork[j]);
}
