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SUBROUTINE sla_DAFIN (STRING, IPTR, A, J)
*+
* - - - - - -
* D A F I N
* - - - - - -
*
* Sexagesimal character string to angle (double precision)
*
* Given:
* STRING c*(*) string containing deg, arcmin, arcsec fields
* IPTR i pointer to start of decode (1st = 1)
*
* Returned:
* IPTR i advanced past the decoded angle
* A d angle in radians
* J i status: 0 = OK
* +1 = default, A unchanged
* -1 = bad degrees )
* -2 = bad arcminutes ) (note 3)
* -3 = bad arcseconds )
*
* Example:
*
* argument before after
*
* STRING '-57 17 44.806 12 34 56.7' unchanged
* IPTR 1 16 (points to 12...)
* A ? -1.00000D0
* J ? 0
*
* A further call to sla_DAFIN, without adjustment of IPTR, will
* decode the second angle, 12deg 34min 56.7sec.
*
* Notes:
*
* 1) The first three "fields" in STRING are degrees, arcminutes,
* arcseconds, separated by spaces or commas. The degrees field
* may be signed, but not the others. The decoding is carried
* out by the DFLTIN routine and is free-format.
*
* 2) Successive fields may be absent, defaulting to zero. For
* zero status, the only combinations allowed are degrees alone,
* degrees and arcminutes, and all three fields present. If all
* three fields are omitted, a status of +1 is returned and A is
* unchanged. In all other cases A is changed.
*
* 3) Range checking:
*
* The degrees field is not range checked. However, it is
* expected to be integral unless the other two fields are absent.
*
* The arcminutes field is expected to be 0-59, and integral if
* the arcseconds field is present. If the arcseconds field
* is absent, the arcminutes is expected to be 0-59.9999...
*
* The arcseconds field is expected to be 0-59.9999...
*
* 4) Decoding continues even when a check has failed. Under these
* circumstances the field takes the supplied value, defaulting
* to zero, and the result A is computed and returned.
*
* 5) Further fields after the three expected ones are not treated
* as an error. The pointer IPTR is left in the correct state
* for further decoding with the present routine or with DFLTIN
* etc. See the example, above.
*
* 6) If STRING contains hours, minutes, seconds instead of degrees
* etc, or if the required units are turns (or days) instead of
* radians, the result A should be multiplied as follows:
*
* for to obtain multiply
* STRING A in A by
*
* d ' " radians 1 = 1D0
* d ' " turns 1/2pi = 0.1591549430918953358D0
* h m s radians 15 = 15D0
* h m s days 15/2pi = 2.3873241463784300365D0
*
* Called: sla_DFLTIN
*
* P.T.Wallace Starlink 1 August 1996
*
* Copyright (C) 1996 Rutherford Appleton Laboratory
*-
IMPLICIT NONE
CHARACTER*(*) STRING
INTEGER IPTR
DOUBLE PRECISION A
INTEGER J
DOUBLE PRECISION AS2R
PARAMETER (AS2R=4.84813681109535993589914102358D-6)
INTEGER JF,JD,JM,JS
DOUBLE PRECISION DEG,ARCMIN,ARCSEC
* Preset the status to OK
JF=0
* Defaults
DEG=0D0
ARCMIN=0D0
ARCSEC=0D0
* Decode degrees, arcminutes, arcseconds
CALL sla_DFLTIN(STRING,IPTR,DEG,JD)
IF (JD.GT.1) THEN
JF=-1
ELSE
CALL sla_DFLTIN(STRING,IPTR,ARCMIN,JM)
IF (JM.LT.0.OR.JM.GT.1) THEN
JF=-2
ELSE
CALL sla_DFLTIN(STRING,IPTR,ARCSEC,JS)
IF (JS.LT.0.OR.JS.GT.1) THEN
JF=-3
* See if the combination of fields is credible
ELSE IF (JD.GT.0) THEN
* No degrees: arcmin, arcsec ought also to be absent
IF (JM.EQ.0) THEN
* Suspect arcmin
JF=-2
ELSE IF (JS.EQ.0) THEN
* Suspect arcsec
JF=-3
ELSE
* All three fields absent
JF=1
END IF
* Degrees present: if arcsec present so ought arcmin to be
ELSE IF (JM.NE.0.AND.JS.EQ.0) THEN
JF=-3
* Tests for range and integrality
* Degrees
ELSE IF (JM.EQ.0.AND.DINT(DEG).NE.DEG) THEN
JF=-1
* Arcminutes
ELSE IF ((JS.EQ.0.AND.DINT(ARCMIN).NE.ARCMIN).OR.
: ARCMIN.GE.60D0) THEN
JF=-2
* Arcseconds
ELSE IF (ARCSEC.GE.60D0) THEN
JF=-3
END IF
END IF
END IF
* Unless all three fields absent, compute angle value
IF (JF.LE.0) THEN
A=AS2R*(60D0*(60D0*ABS(DEG)+ARCMIN)+ARCSEC)
IF (JD.LT.0) A=-A
END IF
* Return the status
J=JF
END
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