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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
INTEGER FUNCTION NUMPTWE(WEST,EAST,GRIDSTEP)
C
C---->
C**** NUMPTWE
C
C Purpose
C -------
C
C Calculate number of grid points in the range from west to east.
C
C
C Interface
C ---------
C
C IRET = NUMPTWE(WEST,EAST,GRIDSTEP)
C
C Input
C -----
C
C WEST - Western boundary in degrees
C EAST - Eastern boundary in degrees
C GRIDSTEP - Grid interval in degrees
C
C
C Output
C ------
C
C Function returns the number of grid points in the east-west
C interval.
C
C
C Method
C ------
C
C The grid is assumed to start at Greenwich.
C
C
C Externals
C ---------
C
C None.
C
C Author
C ------
C
C J.D.Chambers ECMWF Nov 1997
C
C
C Modifications
C -------------
C
C None.
C
C----<
C
IMPLICIT NONE
C
C Function arguments
C
REAL EAST, WEST, GRIDSTEP
C
C Local variables
C
INTEGER NL
REAL*8 DEAST, DWEST
REAL*8 LEFT, RIGHT, STEP, EPS
DATA EPS/1.0E-3/
C
C Statement function
LOGICAL EQUAL
REAL*8 A, B
EQUAL(A,B) = ( ABS(A-B) .LT.EPS )
C
C ------------------------------------------------------------------
C Section 1. Initialise
C ------------------------------------------------------------------
C
100 CONTINUE
C
C Make all longitudes positive for calculation of difference
C
DEAST = EAST
DWEST = WEST
RIGHT = DEAST + 360.0
LEFT = DWEST + 360.0
STEP = GRIDSTEP
IF( RIGHT.LT.LEFT) RIGHT = RIGHT + 360.0
C
C ------------------------------------------------------------------
C Section 2. Calculate the number of points in the interval
C ------------------------------------------------------------------
C
200 CONTINUE
C
C Equal boundaries
C
IF( EQUAL(LEFT,RIGHT) ) THEN
NUMPTWE = 1
GOTO 900
ENDIF
C
C Calculate offset of westernmost gridpoint
C
NL = INT((LEFT+EPS)/STEP)
IF( .NOT. EQUAL(LEFT,(NL*STEP)) ) NL = NL + 1
C
RIGHT = RIGHT - (NL*STEP)
NUMPTWE = INT((RIGHT+EPS)/STEP) + 1
C
C ------------------------------------------------------------------
C Section 9. Return
C ------------------------------------------------------------------
C
900 CONTINUE
C
RETURN
END
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