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    Re: Puzzled by Kaplan's 'Motion of the Observer in Celestial Navigation'
    From: Andrés Ruiz
    Date: 2011 Jun 21, 08:42 +0200
    ANSI C code.

    void AdjustmentOfCelestialCoordinates( double Hc, double Zn, double Be2, double Le2,
      double *GHA_t2, double *Dec_t2 )
    {
    double LHA;
    double sind, cosd;

    sind = SIN( Be2 )*SIN( Hc )+COS( Be2 )*COS( Hc )*COS( Zn );
    cosd = sqrt( 1.0-SQ(sind) );

    LHA = ACOS( ( SIN( Hc )-SIN( Be2 )*sind )/ COS( Be2 )/cosd );
    /* Kaplan: critero de sg !=
    if( 0 <= Zn  && Zn < 180.0 )      *GHA_t2 = -LHA-Le2; 
    else if( 180.0 <= Zn  && Zn <= 360.0 ) *GHA_t2 = +LHA-Le2; 
    */

    if( 0 <= Zn  && Zn < 180.0 ) LHA = 360.0 - LHA; 
    *GHA_t2 = LHA - Le2;

    *Dec_t2 = ATAN( sind/cosd );
    }


    void RunningFix_Kaplan( double t, double GHA, double Dec,
       double Be2, double Le2, double R, double V,
    double tfix, double *GHA_t2, double *Dec_t2 )
    {
    // (B2, L2) -> (d, R) -> (B, L)
    double dt = t - tfix;
    double Be = DRLatitude( Be2, dt, R, V );
    double Le = DRLongitude( Be2, Le2, dt, R, V );//CD: kk no usa Bmedia

    double lha = LocalHourAngle( Le, GHA );
    double HC = Hc( Be, Dec, lha );
    double Zn = Azimut( Be, Dec, HC, lha );

    AdjustmentOfCelestialCoordinates( HC, Zn, Be2, Le2, GHA_t2, Dec_t2 );


    // Comprobacion (Hc, Z)t = (Hc, Z)tfix
    printf( "t:    Hc, Zn = %lf, %lf\n", HC, Zn );

    lha = LocalHourAngle( Le2, *GHA_t2 );
    HC = Hc( Be2, *Dec_t2, lha );
    Zn = Azimut( Be2, *Dec_t2, HC, lha );
    printf( "tfix: Hc, Zn = %lf, %lf\t%.4lf\t%.4lf\n", HC, Zn, Be, Le );
    }

    --
    Andrés Ruiz
    Navigational Algorithms
    http://sites.google.com/site/navigationalalgorithms/
       
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