$LastChangedDate: 27-Juil-2011 $

# CL_fr_qswMat

Inertial frame to QSW local orbital frame transformation matrix

## Calling Sequence

       [M] = CL_fr_qswMat(pos_car,vel_car)

## Description

- Computes the frame transformation matrix M from the inertial reference frame to the QSW local orbital frame.

  The inertial frame is the frame relative to which the satellite's position and velocity are defined. The QSW local frame is built using these position and velocity vectors.

  By convention, multiplying M by coordinates relative to the inertial frame yields coordinates relative to the QSW frame.

- See Local Frames for more details on the definition of local frames.

## Parameters

pos_car:

  satellite's position vector relative to the inertial frame [m] (3xN)

vel_car:

  satellite's velocity vector relative to the inertial frame [m/s] (3xN)

M :

  inertial to QSW local frame transformation matrix (3x3xN)

## Bibliography

- 1) Mecanique spatiale, CNES - Cepadues 1995, Tome I, section 10.2.2.3 (Definition du Repere orbital local)

- 2) CNES - MSLIB FORTRAN 90, Volume O (mo_qsw_geo)

## Authors

- CNES - DCT/SB

## See also

- CL_fr_qsw2inertial

- CL_fr_inertial2qsw

- CL_fr_tnwMat

- CL_fr_inertial2tnw

- CL_fr_tnw2inertial

## Examples

    // Inertial to QSW :
    pos_car = [[3500.e3;2500.e3;5800.e3] , [4500.e3;2100.e3;6800.e3]];
    vel_car = [[1.e3;3.e3;7.e3] , [2.e3;3.e3;6.e3]];
    [M] = CL_fr_qswMat(pos_car,vel_car)
    pos_qsw = M*pos_car;

    // QSW to inertial :
    pos_car = M'*pos_qsw;