SUBROUTINE INTERP1D_LINEAR_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 linear method, from the 
state values at two of the closest source levels.  For simplicity of the algorithm, values 
are also extrapolated using the same algorithm; it is possible instead to clamp the 
values beyond the source levels to the nearest source value, this being controlled by 
extrapEnableDown and extrapEnableUp.  In either case, 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	enables extrapolation at indices below those of vLevelSource. If this argument is .true., the downward extrapolation is performed using the Lagrange algorithm; if .false., the destination state values are set to the nearest source state value.
extrapEnableUp	enables extrapolation at indices above those of vLevelSource. If this argument is .true., the upward extrapolation is performed using the Lagrange algorithm; if .false., the destination state values are set to the nearest source state value.
extrapGuideDown	unused
extrapGuideUp	unused
flux	unused
ExtArraysIn	unused
Output:
stateDerivDestn(dst_ijDim, dstNumLevels)	unused
ExtArraysOut	unused

SEE ALSO