TODO file
List of future (desired) work to be done: 

    o Add to 'inst' a 'CITATION' file for use by the citation function.
        
  
    o Depend / Suggest 'sp', 'gstat' packages
      Suggest / Recommend 'geoR', 'fields' packages

      Depends, Suggests, Imports, Enhances ... packages
      See the information on DESCRIPTION files in the chapter 'Creating R
      packages' of the 'Writing R Extensions' manual.
      
 
    o Plot methods


    o Nonparametric bias-corrected variogram estimation under non-constant trend


    o Kriging


    o Anisotropic variogram models (spatio-temporal case)


    o Additive and partially linear trend models


    o Local Kriging

 
      
#   - '<- update.locpol.bin' 
#   - comprobar valided/dimensiones parmetros rutinas .Fortran
#   - interp.grid.par, predic.locpol.bin y missing  : 
#           Determinar valores x que estn dentro de cuadriculas con datos?
#           Asignar NA si se pretende extrapolar?
#           NA's en FORTRAN?  
#   - revisar h, opcin multiplo espaciado/dimensin rejilla 
#     (units.h=, h(i,i) < 0 ?)
#     (defecto en fortran con valor negativo h(1,1)??)
#   - exemplos
#   - mtodos is: is.locpol.bin, ...
#   - mtodos as: as.data.frame.data.grid, as.bin.data.data.grid, as.bin.data.default, ...
#   - renombrar coords -> coordinates ? (problemas c mtodo S4 de sp?)
#   - n de bins, sm pocos bins:
#         nb <- round(log(ny)/log(2) + 1) # tener en cuenta el n de dimensiones?
#             <- round(log(x)/log(2) + 1) # <- round((log(x)/log(1.1) + 1)^(1/2))^2
#         Regla de Sturges k=1+log2(n)
#         Regla de Scott K=(2n)^(1/3)
#   - drop(x[ok,]) just in case...
#        ok <- complete.cases(x, y) # observations having no missing values across x and y
#        if (any(!ok)) {
#            warning("missing values removed")
#            x <- x[ok,]
#            y <- y[ok]
#            ny <- length(y)
#        }


