Final work for #1563

- Exit if 'regular' (selected/required) and non-regular binning
- Use 5x5x10 flipfield from @sqmeng

common/lib/share/interpolation-lib.c

@@ -440,11 +440,23 @@ struct interpolator_struct *interpolator_load(char *filename,
  interpolator->bin[dim]++; /* count unique values */
  if (interpolator->step[dim] <= 0) 
  interpolator->step[dim] = this_step;
- if (fabs(this_step - interpolator->step[dim]) > interpolator->step[dim]*READ_TABLE_STEPTOL) {
+ if (this_step && fabs(this_step - interpolator->step[dim]) > interpolator->step[dim]*READ_TABLE_STEPTOL) {
  /* difference of this step with the first one is 'large' */
  interpolator->constant_step[dim] = 0; /* not constant step -> kd-tree should be used */
- if (!strcmp(interpolator->method, "NULL") || !strcmp(interpolator->method, "0"))
- strcpy(interpolator->method, "kdtree"); 
+ if (!strcmp(interpolator->method, "NULL") || !strcmp(interpolator->method, "0")) {
+ strcpy(interpolator->method, "kdtree");
+ } else if (!strcmp(interpolator->method, "regular")) { 
+ // We arrived here with 'regular' explicitly user-selected / required (GPU)
+ // which leads to wrong results.
+ fprintf(stderr,"\n\n%s\n\n",
+ "!! interpolation-lib ERROR: !!\n"
+ " You are running the 'regular' interpolation scheme with a file of\n"
+ " non-consistent axis 'binning' along one or more axes.\n"
+ " This combination is not possible.\n"
+ " Please either resample the file to a regular grid or run with 'kdtree'\n"
+ " (NB: kdtree is available on CPU only)");
+ exit(-1);
+ }
  }
  x_prev = x;
  }
@@ -468,18 +480,7 @@ struct interpolator_struct *interpolator_load(char *filename,
  /* assign interpolation technique: 'regular' direct indexing */
  if (!strcmp(interpolator->method, "regular")) {
  interpolator->kdtree = NULL;
- /* Terminate if the dimensions are not equal */
- if (interpolator->bin[0] != interpolator->bin[1] ||
- interpolator->bin[0] != interpolator->bin[2] ||
- interpolator->bin[1] != interpolator->bin[2]) {
- fprintf(stderr,"\n\n%s\n\n",
- "!! interpolation-lib ERROR: !!\n"
- " You are running the 'regular' interpolation scheme\n"
- " with a file of unequal axis dimensions. This will lead to systematic errors!\n"
- " Please either resample the file to achieve this or run with 'kdtree'\n"
- " (kdtree is available on CPU only)");
- exit(-1);
- }
+
  /* store table values onto the grid: each field component is stored on the
  * interpolator->grid, and has size=prod(interpolator->bin)
  */