C+
C NAME:
C	SplineGridY
C PURPOSE:
C	Interpolation of 2D arrays in vertical direction.
C CATEGORY:
C	Interpolation using natural spline
C CALLING SEQUENCE:
	subroutine SplineGridY(iFlag,YN1,YN2,YM1,YM2,NX,NY,ZN,MY,ZM)
C INPUTS:
C	iFlag		integer		1st bit set: flag bad point in output ZM if
C					    nearest grid point in ZN is bad.
C
C					2nd bit set: if the range [YM1,YM2] extends
C					    outside [YN1,YN2] then y-coordinates outside
C					    [YN1,YN2] are mapped back inside
C					    by a mod (YN2-YN1) operation. 
C	YN1		real		y-coordinate of 1st  row of  input ZN
C	YN2		real		y-coordinate of last row of  input ZN
C	YM1		real		y-coordinate of 1st  row of output ZM
C	YM2		real		y-coordinate of last row of output ZM
C	NX		integer		horizontal dimension of ZN
C	NY		integer		vertical dimensions of ZN
C	ZN(NX,NY)	real		fnc-values
C	MY		integer		new vertical dimension
C OUTPUTS:
C	ZM(NX,MY)	real		interpolated fnc-values
C CALLS:
C	ArrR4Step, Say, SplineY
C RESTRICTIONS:
C	The in- and output user-coordinate ranges must be non-zero
C PROCEDURE:
C >	1st bit of iFlag is set: for each grid point of the output grid the
C	nearest grid point of the output grid is determined. If this nearest
C	point was flagged (contained value BadR4()) then the value of the
C	output grid is also flagged.
C	!! `Nearest' means the nearest grid point in the
C	   in the vertical direction only (along a single column).
C
C >	For each column in ZN a spline is calculated, using all valid fnc-values
C	in that column. The ordinate for the spline is assumed to run from
C	YN1 to YN2. The spline is then used to interpolate fnc-values in
C	evenly spaced ordinate values between YM1 and YM2.
C >	If the column dimension is not changed, SplineGridY has the effect of
C	filling in the invalid function values (if 1st bit of iFlag is set)
C MODIFICATION HISTORY:
C	JUL-1993, Paul Hick (UCSD/CASS)
C	APR-1994, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
C	    added argument bFlag to control flagging of function values in the output array
C	MAY-2002, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
C	    added arguments MY and ZM to allow changes in horizontal dimension
C	    Note that the old functionality is retained by setting MY=NY, ZM=ZN
C	    Changed logical argument bFlag to integer argument iFlag. The original bFlag
C	    functionality is now controlled by the first bit in iFlag. The second bit
C	    is now used to contol the mod( YN2-YN1 ) behavior.
C-
	    integer	iFlag
	    real	YN1
	    real	YN2
	    real	YM1
	    real	YM2
	    integer	NX
	    integer	NY
	    real	ZN(NX,NY)		! Input data array
	    integer	MY
	    real	ZM(NX,MY)		! Output data array

	character	cSay*11			/'SplineGridY'/

	parameter	(NMAX = 1000)

	real		YN(NMAX)
	real		YM(NMAX)

	if (max(NY,MY) .gt. NMAX) call Say(cSay,'E','Not enough','scratch space. Increase parameter NMAX')

	call ArrR4Step(YN1,(YN2-YN1)/(NY-1),NY,YN)	! Input Y-coordinates
	call ArrR4Step(YM1,(YM2-YM1)/(MY-1),MY,YM)	! Output X-coordinates

	call SplineY(iFlag,NY,YN,MY,YM,NX,ZN,ZM)

	return
	end