SUBROUTINE INTERP1D_NEARESTNEIGHBOUR_X(numInterpSets, srcNumLevels, 
destNumLevels, src_ijDim, dst_ijDim, vLevelSource, stateSource, stateDerivSource, 
posnDestInSrc, vLevelDestn, stateDestn, stateDerivDestn, extrapEnableDown, 
extrapEnableUp, extrapGuideDown, extrapGuideUp, flux, numExtArraysIn,
numExtArraysOut, ExtArraysIn, ExtArraysOut)

integer, intent(in) :: numInterpSets
integer, intent(in) :: srcNumLevels
integer, intent(in) :: destNumLevels

integer, intent(in) :: src_ijDim
integer, intent(in) :: dst_ijDim

real, dimension(src_ijDim, srcNumLevels), intent(in) :: vLevelSource
real, dimension(src_ijDim, srcNumLevels), intent(in) :: stateSource
real, dimension(src_ijDim, srcNumLevels), intent(in) :: stateDerivSource

integer, dimension(dst_ijDim, destNumLevels), intent(in) :: posnDestInSrc
real, dimension(dst_ijDim, destNumLevels), intent(in) :: vLevelDestn
real, dimension(dst_ijDim, destNumLevels), intent(out) :: stateDestn
real, dimension(dst_ijDim, destNumLevels), intent(out) :: stateDerivDestn

logical, intent(in) :: extrapEnableDown, extrapEnableUp
real, intent(in) :: extrapGuideDown, extrapGuideUp

external flux

integer, intent(in) :: numExtArraysIn
integer, intent(in) :: numExtArraysOut
real, dimension(src_ijDim, numExtArraysIn), intent(in)  :: ExtArraysIn
real, dimension(dst_ijDim, numExtArraysOut), intent(out) :: ExtArraysOut
DESCRIPTION 
For each destination level, a state value is interpolated, using a nearest-neighbour method, 
from the state value at the closest source level.  The nearest-neighbour method consists 
of identifying the source co-ordinate that is closest to the sought co-ordinate, and 
assigning the state value of that source co-ordinate as the sought value. In the case of 
this particular algorithm, clamping the values beyond the source levels to the nearest 
source value (as do the other interpolation algorithms) is identical to the nearest-neighbour 
algorithm. Therefore, this is done automatically, independently of extrapEnableDown and 
extrapEnableUp.  These values could be overwritten by any of the extrapolation routines.

Author: Jeff Blezius - revised Oct 2003
ARGUMENTS

It can be noted that the arguments to all of the Interp1D_* and Extrap1D_* routines are identical, for ease of switching a call from one to another of them. You should examine the generic description of the arguments. The following are uses of the generic arguments that are specific to this routine:

Input:
stateDerivSource(src_ijDim, srcNumLevels)	unused
extrapEnableDown	unused
extrapEnableUp	unused
extrapGuideDown	unused
extrapGuideUp	unused
flux	unused
ExtArraysIn	unused
Output:
stateDerivDestn(dst_ijDim, dstNumLevels)	unused
ExtArraysOut	unused

SEE ALSO