NASA Ocean Color

ocssw V2022

       SUBROUTINE xthird(T,TR,ES,ET,XS)   
 C  VERSION OF 4/1/85
 C  PURPOSE   
 C    COMPUTES POSITION OF PERTURBING THIRD BODY
 C  INPUT 
 C    T      = CURRENT TIME (SEC)
 C    TR     = REFERENCE TIME FOR INITIAL SETTING OF THE
 C             GREENWICH HOUR ANGLE, AND THE MEAN ANOMALIES OF
 C             THE ANALYTICAL LUNI-SOLAR EPHEMERIDES (SEC)
 C    ES     = 7-D ORBITAL ELEMENT SET OF THIRD BODY
 C      (1)  = SEMI-MAJOR AXIS (KM)
 C      (2)  = ECCENTRICITY OF THE THIRD BODY
 C      (3)  = INCLINATION OF THE THIRD BODY RELATIVE TO THE PLANET (RAD)
 C      (4)  = LONGITUDE OF ASCENDING NODE OF THE THIRD BODY (RAD)
 C      (5)  = AGRUMENT OF PERIAPSIS OF THE THIRD BODY (RAD)
 C      (6)  = MEAN ANOMALY OF THE THIRD BODY AT TR (RAD)
 C      (7)  = MEAN MOTION (RAD/SEC)
 C    ET     = 8-D ELEMENTS TO TRANFORM ORBITAL ELEMENTS TO CART.
 C             COORD, THIS IS SET UP BY SETTHD ROUTINE
 C      (1)  = L1, COS(NODE)*COS(W) - SIN(NODE)*SIN(W)*COS(I)  
 C      (2)  = M1, SIN(NODE)*COS(W) + COS(NODE)*SIN(W)*COS(I)  
 C      (3)  = N1, SIN(W)*SIN(I)   
 C      (4)  = L2, -COS(NODE)*SIN(W) - SIN(NODE)*COS(W)*COS(I) 
 C      (5)  = M2, -SIN(NODE)*SIN(W) + COS(NODE)*COS(W)*COS(I) 
 C      (6)  = N2, COS(W)*SIN(I)   
 C      (7)  = SEMI-MINOR AXIS, A*SQRT(1-E*E)  
 C  OUTPUT
 C    XS     = 3-D CARTESIAN STATE OF 3RD BODY (KM)
 C  CALLED BY SUBROUTINES 
 C    DER   
 C  CALL SUBROUTINES  
 C    KEPLER
 C  REFERENCES
 C    JPL EM 312/87-153, 20 APRIL 1987
 C    ORBITAL MOTION, A. E. ROY, 1978, P.102
 C  ANALYSIS
 C    J. H. KWOK - JPL  
 C  PROGRAMMER
 C    J. H. KWOK - JPL  
 C  PROGRAM MODIFICATION  
 C    NONE  
 C  COMMENTS  
 C    NONE  
 C   
       IMPLICIT DOUBLE PRECISION (a-h,o-z)   
       dimension es(7),et(7),xs(3)   
       DATA tpi/6.283185307179586d0/   
       am=dmod(es(6)+es(7)*(t-tr),tpi)   
       CALL kepler(am,es(2),ea,se,ce)
       DO 10 i=1,3   
    10 xs(i)=es(1)*et(i)*(ce-es(2))+et(7)*et(i+3)*se 
       RETURN
       END

xthird

subroutine xthird(T, TR, ES, ET, XS)

Definition: xthird.f:2

kepler

subroutine kepler(AM, E, EA, SE, CE)

Definition: kepler.f:2

dmod

double dmod(double a, double p)

Description:

Definition: nav.c:23