$LastChangedDate: 27-Juil-2011 $

# CL_gm_eclipseCheck

Hidden fraction of a body (eclipsed by another body), as seen from an observer

## Calling Sequence

       [rat_ecl] = CL_gm_eclipseCheck(pos_obs, pos1, pos2, sr1, sr2)

## Description

- Computes the hidden fraction of a body (eclipsed by another body), as seen from an observer:

  - 1.0 : 100% of the first body is eclipsed

  - 0.7 : 70% of the first body is eclipsed

  - 0.0 : 0% of the first body is eclipsed

  The two bodies are assumed spherical

## Parameters

pos_obs:

  Position of observer (3xN or 3x1)

pos1:

  Position of centre of sphere1 (3xN or 3x1)

pos2:

  Position of centre of sphere2 (3xN or 3x1)

sr1:

  Radius of sphere1 (1x1 or 1xN)

sr2:

  Radius of sphere2 (1x1 or 1xN)

rat_ecl:

  Hidden fraction of body1, as seen from pos_obs (3xN)

## Authors

- CNES - DCT/SB

## See also

## Examples

    // Fraction of Sun eclipsed by Earth (from an observer in space):
    theta = linspace(165*%CL_deg2rad, 175*%CL_deg2rad, 100);
    pos_obs = 42000.e3 * [ cos(theta) ; sin(theta) ; zeros(theta) ];
    pos1 = %CL_au * [ 1 ; 0 ; 0 ]; // Sun
    sr1 = %CL_radiusSun;
    pos2 = [0 ; 0 ; 0]; // Earth
    sr2 = %CL_eqRad;
    rat_ecl = CL_gm_eclipseCheck(pos_obs, pos1, pos2, sr1, sr2);
    scf();
    plot(theta*%CL_rad2deg, rat_ecl, "o");