remap_define_reg2d: bug fix for non monotonic increasing longitudes.

src/remaplib.cc

@@ -570,6 +570,11 @@ void remap_define_reg2d(int gridID, remapgrid_t *grid)
   grid_to_radian(yunits, nx, grid->reg2d_center_lon, "grid reg2d center lon");
   grid_to_radian(yunits, ny, grid->reg2d_center_lat, "grid reg2d center lat");
 
+  if ( grid->reg2d_center_lon[nx-1] < grid->reg2d_center_lon[0] )
+    for ( long i = 1; i < nx; ++i )
+      if ( grid->reg2d_center_lon[i] < grid->reg2d_center_lon[i-1] )
+        grid->reg2d_center_lon[i] += PI2;
+
   if ( grid->is_cyclic ) grid->reg2d_center_lon[nx] = grid->reg2d_center_lon[0] + PI2;
 
   grid->reg2d_corner_lon = (double*) Malloc(nxp1*sizeof(double));