This page was created by the IDL library routine mk_html_help2.

Last modified: Fri Sep 18 01:15:20 2009.


Directory Listing of Routines


Routine Descriptions

ENP_CRIB

[Next Routine] [List of Routines]
Procedure: enp_crib.pro

Purpose:  A crib showing how to transform data into the ENP and PEN coordinate systems. 

   E: sat to earth (in-plane)
   N: east (in-plane)
   P: north (perpendicular to plane).

  Defined relative to another coordinate system:
   P_sat = spacecraft position in geocentric interial coordinate system
   V_sat = deriv(P_sat)   (spacecraft velocity in the same coordinate system.)

   P_enp = P_sat cross V_sat
   E_enp = -P_sat
   N_enp = P_enp cross P_sat

Notes:

 $LastChangedBy: pcruce $
 $LastChangedDate: 2009-09-16 15:18:08 -0700 (Wed, 16 Sep 2009) $
 $LastChangedRevision: 6741 $
 $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/special/enp/enp_crib.pro $

(See ssl_general/cotrans/special/enp/enp_crib.pro)


ENP_MATRIX_MAKE

[Previous Routine] [List of Routines]
Procedure: enp_matrix_make

Purpose: 
  Creates a set of matrices that will rotate data from the input coordinate system into
  ENP.
   E: sat to earth (in-plane)
   N: east (in-plane)
   P: north (perpendicular to plane).

  Defined relative to another coordinate system:
   P_sat = spacecraft position in geocentric interial coordinate system
   V_sat = deriv(P_sat)   (spacecraft velocity in the same coordinate system.)

   P_enp = P_sat cross V_sat
   E_enp = -P_sat
   N_enp = P_enp cross P_sat
   
Inputs:
  pos_tvarname:  Tplot Variable storing the spacecraft position in an intertial earth-centered cartesian coordinate system(like gei)
                 You can use globbing to pass multiple position vectors simultaneously. ('th?_state_pos')  
  
Outputs: 
  xxx2enp transformation matrix
  
 Keywords:
   /pen  : reorders the basis vectors so that they transform to and from PEN rather than ENP
   fail=fail: Will be set to 1 if operation failed, returns 0 if operation succeeded.  Will not signal failure if
        at least one input was processed.
  suffix: The suffix to be appended to the tplot variables that the output matrices will be stored in.
         (Default: '_enp_mat' or '_pen_mat')
  newname: The name of the output matrix.  If this keyword is used with multiple input values, the outputs
          may overwrite each other.  So you should only set this keyword if there is a single value for the state input.
  velocity_tvar:  Set this keyword to the name of a tplot variable or variables that store velocities matching the positions.
           This way the routine doesn't need to calculate the velocity using derivatives  
   
Notes:
  Because velocity is calculated using the derivative of position,
  there should be a small numerical error at the end points of the time series

 $LastChangedBy: pcruce $
 $LastChangedDate: 2009-09-16 12:37:46 -0700 (Wed, 16 Sep 2009) $
 $LastChangedRevision: 6739 $
 $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/special/enp/enp_matrix_make.pro $

(See ssl_general/cotrans/special/enp/enp_matrix_make.pro)