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C Copyright 1981-2016 ECMWF.
C
C This software is licensed under the terms of the Apache Licence
C Version 2.0 which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
C
C In applying this licence, ECMWF does not waive the privileges and immunities
C granted to it by virtue of its status as an intergovernmental organisation
C nor does it submit to any jurisdiction.
C
INTEGER FUNCTION IGBESS(KTRUNC, PBESJ0, KPR, KERR)
C
C---->
C**** *IGBESS*
C
C PURPOSE
C _______
C
C Computes initial approximations to Gaussian latitudes.
C
C INTERFACE
C _________
C
C IERR = IGBESS(KTRUNC, PBESJ0, KPR, KERR)
C
C Input parameters
C ________________
C
C KTRUNC - This is the number of zeros of the J0 Bessel
C function required.
C
C
C KPR - The debug print switch.
C 0 , No debugging output.
C 1 , Produce debugging output.
C
C KERR - The error control flag.
C -ve, No error message. Return error code.
C 0 , Hard failure with error message.
C +ve, Print error message. Return error code.
C
C Output parameters
C ________________
C
C PBESJ0 - The output array of zeros of the J0 Bessel function.
C
C Return Value
C ____________
C
C The error indicator (INTEGER).
C
C Error and Warning Return Values
C _______________________________
C
C None
C
C Common block usage
C __________________
C
C None
C
C EXTERNALS
C _________
C
C INTLOG(R) - Logs messages.
C
C METHOD
C ______
C
C The first JPLOOK values are obtained from a look-up table
C (ZPBES). Any additional values requested are approximated by
C adding PI (3.14159...) to the previous value.
C
C REFERENCE
C _________
C
C None
C
C COMMENTS
C ________
C
C This routine is adapted from that in the old Marsint library.
C The interface and the variable names have been modified.
C
C Program contains sections 0 to 2 and 9
C
C AUTHOR
C ______
C
C K. Fielding *ECMWF* Oct 1993
C
C MODIFICATIONS
C _____________
C
C None
C
C----<
C _______________________________________________________
C
C* Section 0. Definition of variables.
C _______________________________________________________
C
IMPLICIT NONE
C
#include "jparams.h"
#include "parim.h"
C
C Dummy arguments
INTEGER KTRUNC, KPR, KERR
REAL PBESJ0 (*)
C
C Local variables
INTEGER ILOOK
INTEGER JAPPRX, JLOOK
INTEGER JPROUTINE
PARAMETER (JPROUTINE = 24400)
REAL ZPBES (JPLOOK)
DATA ZPBES / 2.4048255577E0, 5.5200781103E0,
1 8.6537279129E0, 11.7915344391E0, 14.9309177086E0,
2 18.0710639679E0, 21.2116366299E0, 24.3524715308E0,
3 27.4934791320E0, 30.6346064684E0, 33.7758202136E0,
4 36.9170983537E0, 40.0584257646E0, 43.1997917132E0,
5 46.3411883717E0, 49.4826098974E0, 52.6240518411E0,
6 55.7655107550E0, 58.9069839261E0, 62.0484691902E0,
7 65.1899648002E0, 68.3314693299E0, 71.4729816036E0,
8 74.6145006437E0, 77.7560256304E0, 80.8975558711E0,
9 84.0390907769E0, 87.1806298436E0, 90.3221726372E0,
A 93.4637187819E0, 96.6052679510E0, 99.7468198587E0,
1 102.8883742542E0, 106.0299309165E0, 109.1714896498E0,
2 112.3130502805E0, 115.4546126537E0, 118.5961766309E0,
3 121.7377420880E0, 124.8793089132E0, 128.0208770059E0,
4 131.1624462752E0, 134.3040166383E0, 137.4455880203E0,
5 140.5871603528E0, 143.7287335737E0, 146.8703076258E0,
6 150.0118824570E0, 153.1534580192E0, 156.2950342685E0 /
C
C _______________________________________________________
C
C* Section 1. Extract initial values from look up table
C _______________________________________________________
C
100 CONTINUE
C
IF (KPR.GE.1) CALL INTLOG(JP_DEBUG,'IGBESS: Section 1.',JPQUIET)
C
IGBESS = 0
C
IF (KPR .GE. 1) CALL INTLOG(JP_DEBUG,
X 'IGBESS: No.values requested = ',KTRUNC)
C
ILOOK = MIN (KTRUNC, JPLOOK)
C
DO 110 JLOOK = 1, ILOOK
PBESJ0(JLOOK) = ZPBES(JLOOK)
110 CONTINUE
C
C _______________________________________________________
C
C* Section 2. Approximate any extra values required
C _______________________________________________________
C
200 CONTINUE
C
IF(KPR.GE.1) CALL INTLOG(JP_DEBUG,'IGBESS: Section 2.',JPQUIET)
C
DO 210 JAPPRX = ILOOK + 1, KTRUNC
PBESJ0(JAPPRX) = PBESJ0(JPLOOK) + PPI*(JAPPRX - ILOOK)
210 CONTINUE
C
C _______________________________________________________
C
C* Section 9. Return to calling routine. Format statements
C _______________________________________________________
C
900 CONTINUE
C
IF(KPR.GE.1) CALL INTLOG(JP_DEBUG,'IGBESS: Section 9.',JPQUIET)
C
RETURN
END
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