NASA Ocean Color

ocssw V2022
       SUBROUTINE coord(X,GM,Y)
 C  VERSION OF 4/1/85
 C  PURPOSE
 C    TRANSFORM ORBITAL ELEMENT A,E,I,CAPW,W,EA TO CARTESIAN COORD
 C    X,Y,Z,XD,ZD,YD.
 C  INPUT
 C    X(1)   = A, SEMI-MAJOR AXIS
 C     (2)   = E, ECCENTRICITY
 C     (3)   = I, INCLINATION (RAD)
 C     (4)   = CAPW, LONGITUDE OF ASCENDING NODE (RAD)
 C     (5)   = W, ARGUMENT OF PERIAPSIS (RAD)
 C     (6)   = EA, ECCENTRIC ANOMALY (RAD)
 C    GM     = GRAVITATIONAL CONSTANT * MASS OF PLANET (KM**3/SEC**2)
 C  OUTPUT
 C    Y(1)   = X (KM)
 C     (2)   = Y (KM)
 C     (3)   = Z (KM)
 C     (4)   = XD (KM/SEC)
 C     (5)   = YD (KM/SEC)
 C     (6)   = ZD (KM/SEC)
 C  CALL SUBROUTINES
 C    NONE
 C  REFERENCES
 C    JPL EM 312/87-153, 20 APRIL 1987
 C    ORBITAL MOTION, A. E. ROY, 1978, PAGE 102
 C  ANALYSIS
 C    J. H. KWOK - JPL
 C  PROGRAMMER
 C    J. H. KWOK - JPL
 C  PROGRAM MODIFICATIONS
 C    NONE
 C
       IMPLICIT DOUBLE PRECISION (a-h,o-z)
       dimension x(6),y(6),td(8)
       DATA one/1.d0/
       cc=dcos(x(4))
       sc=dsin(x(4))
       cw=dcos(x(5))
       sw=dsin(x(5))
       ci=dcos(x(3))
       si=dsin(x(3))
       td(1)=cc*cw-sc*sw*ci
       td(2)=sc*cw+cc*sw*ci
       td(3)=sw*si
       td(4)=-cc*sw-sc*cw*ci
       td(5)=-sc*sw+cc*cw*ci
       td(6)=cw*si
       td(7)=dsqrt(one-x(2)**2)*x(1)
       td(8)=dsqrt(gm/x(1)**3)
       ce=dcos(x(6))
       se=dsin(x(6))
       r=x(1)*(one-x(2)*ce)
       DO 10 i=1,3
       y(i)=x(1)*td(i)*(ce-x(2))+td(7)*td(i+3)*se
    10 y(i+3)=x(1)*td(8)*(td(7)*ce*td(i+3)-x(1)*se*td(i))/r
       RETURN
       END
  
coord
Definition: dataday.h:40