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C Copyright 1981-2007 ECMWF
C
C Licensed under the GNU Lesser General Public License which
C incorporates the terms and conditions of version 3 of the GNU
C General Public License.
C See LICENSE and gpl-3.0.txt for details.
C
SUBROUTINE SH2SH(UFLDIN, KRESIN, UFLDOU, KRESOU)
IMPLICIT NONE
C
C---->
C**** SH2SH
C
C Purpose
C _______
C
C This routine produces a field of spectral coefficients in UFLDOU
C of truncation KRESOU from a field of spectral coeeficients in
C UFLDIN of truncation KRESIN.
C
C
C Interface
C _________
C
C CALL SH2SH(UFLDIN, KRESIN, UFLDOU, KRESOU)
C
C
C Input parameters
C ________________
C
C UFLDIN - field of spectral coefficients
C KRESIN - truncation of input field
C KRESOU - truncation of output field
C
C
C Output parameters
C ________________
C
C UFLDOU - field of spectral coefficients
C
C
C Common block usage
C __________________
C
C None
C
C
C Method
C ______
C
C If the input truncation is greater than (or equal to) the output
C truncation, coefficients are transferred reduced for the output.
C
C If the input truncation is less than the output truncation,
C all coefficients are transferred and padded with zeroes for the
C output.
C
C
C Externals
C _________
C
C None
C
C
C Reference
C _________
C
C None
C
C
C Comments
C ________
C
C Arrays for the input and output fields must be defined large
C enough for the coefficients implied by the truncations. Thus
C the dimension for UFLDOU must be at least:
C ( KRESOU + 1) * ( KRESOU + 2 ) /2
C
C
C Author
C ______
C
C J.D.Chambers ECMWF 8th Nov 1993
C
C
C Modifications
C _____________
C
C None
C
C----<
C _______________________________________________________
C
C
C* Section 0. Definition of variables.
C _______________________________________________________
C
C* Prefix conventions for variable names
C
C Logical L (but not LP), global or common.
C O, dummy argument
C G, local variable
C LP, parameter.
C Character C, global or common.
C H, dummy argument
C Y (but not YP), local variable
C YP, parameter.
C Integer M and N, global or common.
C K, dummy argument
C I, local variable
C J (but not JP), loop control
C JP, parameter.
C Real A to F and Q to X, global or common.
C P (but not PP), dummy argument
C Z, local variable
C PP, parameter.
C Complex U, dummy argument
C
C _______________________________________________________
C
C Subroutine arguments
COMPLEX UFLDIN(*),UFLDOU(*)
INTEGER KRESIN, KRESOU
C
C Local variables
INTEGER ITINP1, ITOUP1, ILIM, IMLIM, IMN, IMP, IADD
INTEGER JM, JN
C
C _______________________________________________________
C
C
C* Section 1. Initialization
C _______________________________________________________
C
100 CONTINUE
C
C Initialize loop control variables
C
ITINP1 = KRESIN + 1
ITOUP1 = KRESOU + 1
ILIM = ITOUP1
IMLIM = ITOUP1
IMN = 1
IMP = 1
C
C _______________________________________________________
C
C
C* Section 2. Computation.
C _______________________________________________________
C
200 CONTINUE
C
C Check if desired output truncation greater than input ...
C
IADD = KRESIN - KRESOU
IF ( IADD .GE. 0 ) THEN
C
C ... input truncation not less than desired output ...
C ... move truncated lines of coefficients
DO 230 JM = 1, IMLIM
DO 220 JN = JM, ILIM
UFLDOU(IMP) = UFLDIN(IMN)
IMP = IMP + 1
IMN = IMN + 1
220 CONTINUE
C Skip coefficients being truncated
IMN = IMN + IADD
230 CONTINUE
C
C ... input truncation is less than desired output ...
C ... pad each output line of coefficients with zeroes
ELSE
DO 250 JM = 1, IMLIM
DO 240 JN = JM, ILIM
IF ( JN .GT. ITINP1 .OR. JM .GT. ITINP1) THEN
C At end of input coefficients in
C current row, then set values to
C zero in output
UFLDOU(IMP) = 0.0
ELSE
UFLDOU(IMP) = UFLDIN(IMN)
IMN = IMN + 1
ENDIF
IMP = IMP + 1
240 CONTINUE
250 CONTINUE
ENDIF
C
C _______________________________________________________
C
C
C* Section 9. Return to calling routine.
C _______________________________________________________
C
900 CONTINUE
RETURN
END
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