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!
! THIS IS DragoRT1.0, THE IMPLEMENTATION OF THE PBMC ALGORITHM DESCRIBED IN:
!
! PRE-CONDITIONED BACKWARD MONTE CARLO SOLUTIONS TO RADIATIVE 
! TRANSPORT IN PLANETARY ATMOSPHERES. FUNDAMENTALS: 
! SAMPLING OF PROPAGATION DIRECTIONS IN POLARISING MEDIA
! BY A. GARCIA MUNOZ & F.P. MILLS
! ASTRONOMY & ASTROPHYSICS, 2015, 573, A72
!
! THE MANUSCRIPT IS ALSO AVAILABLE AT ASTRO.PH, ID: 1408.4019
!
! DragoRT1.0 M CALCULATES THE STOKES VECTOR FOR OUTGOING RADIATION 
! REFLECTED FROM A PLANE-PARALLEL ATMOSPHERE
!
! THE REFERENCE INCLUDES NUMEROUS TEST CASES THAT EXPLORE THE
! ALGORITHM'S PERFORMANCE FOR BOTH RAYLEIGH AND MIE SCATTERING MEDIA
!
! LAST MODIFIED ON 01/AUGUST/2014
!
! FOR A SKETCH OF THE RELEVANT GEOMETRICAL ANGLES, SEE FIG. 5 IN THE REFERENCE.
! IN BRIEF: 
!    COSPOLOBS & COSPOLSUN ARE THE COSINES OF THE OBSERVER AND 
!                                          SOLAR POLAR ANGLES
!    AZIMUTH IS THE AZIMUTH ANGLE BETWEEN THE OBSERVER AND SOLAR PLANES.       
!
! THIS PACKAGE IS ACCOMPANIED BY:
!   * INPUT FILES: INPUT_hazeL.txt, INPUT_L13.txt, INPUT_L60.txt;
!     THEY CONTAIN EXPLANATIONS TO THE INPUT PARAMETERS. 
!     COPY INPUT_XXXX.txt INTO INPUT.dat TO EXECUTE SOME OF THE EXAMPLES 
!     DESCRIBED IN THE REFERENCE
!   * FILES WITH SCATTERING MATRIX PROPERTIES: 
!                phF_hazeL.txt, phF_L13.txt, phF_L60.txt
!   * SCRIPT FOR COMPILATION IN GFORTRAN (myscript)
!
! FOR RAYLEIGH ATMOSPHERES, ONE CAN SET UP A SIMILAR phF FILE. OTHERWISE, 
! ONE CAN INCORPORATE THE RELEVANT SCATTERING MATRIX BY UNCOMMENTING 
! THE 9 ROWS FOLLOWING:
!   "FOR RAYLEIGH SCATTERING ATMOSPHERES, UNCOMMENT THE FOLLOWING 9 ROWS"
! IN THE FORTRAN CODE
!
! TO COMPILE THE PROGRAM WITH GFORTRAN, EXECUTE FROM A TERMINAL: ./myscript 
! TO RUN THE PROGRAM, EXECUTE FROM A TERMINAL: ./PBMC.exe
!
! THE PROGRAM WILL OUTPUT THE FILE OUT.DAT WITH A SUMMARY OF THE 
! INPUT PARAMETERS AND THE OUTPUT STOKES VECTORS. NOTE THAT THE DEFINITION 
! HERE OF POSITIVE V STOKES ELEMENT DIFFERS FROM THE DEFINITION 
! IN THE SOURCES FOR THE TEST CASES.
!
! THE PROGRAM IS FREELY AVAILABLE FOR ANY NON-FOR-PROFIT APPLICATION.
! IF YOU USE IT, PLEASE GIVE CREDIT TO THE ABOVE REFERENCE.
!
! FOR COMMENTS, QUESTIONS, ETC, PLEASE CONTACT A. GARCIA MUNOZ ON: 
!                               TONHINGM@GMAIL.COM
! ALSO, IF YOU SPOT A BUG OR INCONSISTENCY, PLEASE DROP ME AN EMAIL.
! THE INTENT IS TO UPDATE DragoRT TO IMPROVE ITS PERFORMANCE AND INCLUDE 
! NEW FEATURES, SO FEEL WELCOME TO DROP ME AN EMAIL TO FIND OUT 
! ABOUT THE LATEST VERSION.
!
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