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MODULE orbite_m |
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IMPLICIT NONE |
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CONTAINS |
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pure SUBROUTINE orbite(xjour, longi, dist) |
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! From phylmd/orbite.F, version 1.1.1.1, 2004/05/19 12:53:08 |
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! Author: Z. X. Li (LMD/CNRS) |
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! Date: 1993/08/18 |
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! Pour un jour donn\'e, calcule la longitude vraie de la Terre et |
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! la distance Terre-Soleil. |
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use nr_util, only: deg_to_rad, rad_to_deg |
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USE yomcst, ONLY: r_ecc, r_peri |
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REAL, INTENT (IN):: xjour ! jour de l'ann\'ee \`a compter du premier janvier |
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REAL, INTENT (OUT):: longi |
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! longitude vraie de la Terre dans son orbite solaire, par rapport |
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! au point vernal (21 mars), en degr\'es |
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REAL, INTENT (OUT), OPTIONAL:: dist ! distance terre-soleil, en ua |
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! Local: |
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REAL xl, xllp, xee, xse, ranm |
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!---------------------------------------------------------------------- |
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xl = r_peri + 180. |
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xllp = xl * deg_to_rad |
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xee = r_ecc**2 |
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xse = sqrt(1. - xee) |
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ranm = 2. * ((r_ecc / 2 + r_ecc * xee / 8.) * (1. + xse) * sin(xllp) & |
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- xee / 4. * (0.5 + xse) * sin(2.*xllp) + r_ecc * xee / 8. & |
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* (1. / 3. + xse) * sin(3. * xllp)) + (xjour - 81.) * deg_to_rad - xllp |
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xee = xee * r_ecc |
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longi = ranm + (2. * r_ecc - xee / 4.) * sin(ranm) & |
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+ 5. / 4. * r_ecc**2 * sin(2 * ranm) + 13. / 12. * xee * sin(3. * ranm) |
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IF (present(dist)) dist = (1 - r_ecc**2) / (1 + r_ecc * cos(longi)) |
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longi = longi * rad_to_deg + xl |
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END SUBROUTINE orbite |
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END MODULE orbite_m |