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Interpolation/

extrapolate.pro

extrapolate data (zinput) where maskinput equal 0 by filling step by step the coastline points with the mean value of the 8 neighbors (weighted by their mask values).

extrapolate Interpolation

result = extrapolate(zinput, maskinput[, nb_iteration], X_PERIODIC=scalar, 0 or 1, MINVAL=scalar, MAXVAL=scalar, GE0=scalar 0 or 1, _EXTRA=_EXTRA)

Return value

the extrapolated 2d array

Parameters

zinput        in required type: 2d array

data to be extrapolate

maskinput        in required type: 2d array or -1

a 2D array, the land-sea mask of the output data (1 on ocean, 0 on land) put -1 if input data are not masked

nb_iteration        in optional type: integer default: large enough to fill everything

Maximum number of iterations done in the extrapolation process. If there is no more masked values we exit extrapolate before reaching nb_iteration

Keywords

X_PERIODIC        type: scalar, 0 or 1 default: 0

put 1 to specify that the data are periodic along x axis

MINVAL        type: scalar default: not used

to specify a minimum value to the extrapolated values

MAXVAL        type: scalar default: not used

to specify a maximum value to the extrapolated values

GE0        type: scalar 0 or 1 default: 0

put 1 to force the extrapolated values to be larger than 0, same as using minval=0.

_EXTRA       

to be able to call extrapolate with _extra keyword

Examples

 IDL> a=extrapolate(dist(jpi,jpj),tmask[*,*,0],/x_periodic)
 IDL> tvplus, a
 IDL> tvplus, a*(1-tmask[*,*,0])
 get the coastline:
 IDL> a=extrapolate(tmask[*,*,0],tmask[*,*,0],1,/x_periodic)
 IDL> tvplus, a-tmask[*,*,0]

    

Version history

Version

$Id: extrapolate.pro 295 2007-09-25 10:16:00Z pinsard $

History

Originaly written by G. Roullet Sebastien Masson (smasson@lodyc.jussieu.fr)

 


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