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Last modified: Wed Jul 4 01:15:21 2012.

# Directory Listing of Routines

# ssl_general/cotrans

- COTRANS
- COTRANS_GET_COORD
- COTRANS_LIB[1]
- COTRANS_LIB[2]
- COTRANS_LIB[2]
- COTRANS_LIB[3]
- COTRANS_LIB[4]
- COTRANS_LIB[5]
- COTRANS_LIB[6]
- COTRANS_LIB[7]
- COTRANS_LIB[8]
- COTRANS_LIB[9]
- COTRANS_LIB[10]
- COTRANS_LIB[11]
- COTRANS_LIB[12]
- COTRANS_LIB[13]
- COTRANS_LIB[14]
- COTRANS_LIB[15]
- COTRANS_LIB[16]
- COTRANS_LIB[17]
- COTRANS_LIB[18]
- COTRANS_LIB[19]
- COTRANS_LIB[20]
- COTRANS_LIB[21]
- COTRANS_LIB[22]
- COTRANS_LIB[23]
- COTRANS_SET_COORD
- GEO2MAG
  Convert from geographic to geomagnetic coordinates
- HDZ2GEO
- MAG2GEO.PRO
  Convert from geomagnetic to geographic coordinates
- SPG2SSL

# Routine Descriptions

## COTRANS

[Next Routine] [List of Routines]

    procedure: cotrans, name_in, name_out [, time]

    Purpose: geophysical coordinate transformations

             GEI<-->GSE;
             GSE<-->GSM;
             GSM<-->SM;
             GEI<-->GEO;
             GEO<-->MAG;
             interpolates the spinphase, right ascension, declination
             updates coord_sys atribute of output tplot variable.

    inputs

       name_in 	... data in the input coordinate system (t-plot variable name,
                                                            or array)
       name_out    ... variable name for output            (t-plot variable name,
                                                            or array)
       time        ... optional input: array of times for input values, if provided
                       then the first parameter is an array, and the second
                       parameter is a named variable to contain the output array.

    keywords:
       TRANSFORMATIONS

    	/GEI2GSE
    	/GSE2GEI

    	/GSE2GSM
    	/GSM2GSE

     /GSM2SM
     /SM2GSM

     /GEI2GEO
     /GEO2GEI

     /GEO2MAG
     /MAG2GEO

     /IGNORE_DLIMITS: set so it won't require the coordinate
    system of the input tplot variable to match the coordinate
    system from which the data is being converted

    Examples:

          cotrans,'tha_fgl_gse','tha_fgl_gsm',/GSE2GSM
          cotrans,'tha_fgl_gsm','tha_fgl_gse',/GSM2GSE

          cotrans,'tha_fgl_gse','tha_fgl_gei',/GSE2GEI
          cotrans,'tha_fgl_gei','tha_fgl_gse',/GEI2GSE

          cotrans,'tha_fgl_gsm','tha_fgl_sm',/GSM2SM
          cotrans,'tha_fgl_sm','tha_fgl_gsm',/SM2GSM

    Notes: under construction!!
           clrussell, 03-30-12, added GEO2MAG and MAG2GEO conversions

    Written by: Hannes Schwarzl & Patrick Cruce(pcruce@igpp.ucla.edu)

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/cotrans.pro $

(See ssl_general/cotrans/cotrans.pro)

## COTRANS_GET_COORD

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    	Function: COTRANS_GET_COORD

    	Purpose:  determine the coordinate system of data by
                     examining the contents of it's DLIMIT structure.

    	Calling Sequence:
    		tplot_var = 'tha_eff'
    		get_data, tplot_var, data=d, limit=l, dlimit=dl
    		coord = cotrans_get_coord( dl)
                   ; -- or --
                   coord = cotrans_get_coord('tha_eff')

    	Arguements:
    		DL, Anonymous STRUCT, or tplot variable name.

    	Notes:
    		None.

     $LastChangedBy: kenb-mac $
     $LastChangedDate: 2007-05-01 15:11:55 -0700 (Tue, 01 May 2007) $
     $LastChangedRevision: 622 $
     $URL $

(See ssl_general/cotrans/cotrans_get_coord.pro)

## COTRANS_LIB[10]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: subSM2GSM

    Purpose: transforms data from SM to GSM

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[11]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: subGEI2GEO

    Purpose: transforms data from GEI to GEO

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[12]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: subGEO2GEI

    Purpose: transforms data from GEO to GEI

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[13]

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    procedure: subGEO2MAG

    Purpose: transforms data from GEO to MAG

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[14]

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    procedure: subMAG2GEO

    Purpose: transforms data from MAG to GEO

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[15]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: csundir_vect

    Purpose: calculates the direction of the sun
             (vectorized version of csundir from ROCOTLIB by
              Patrick Robert)

    INPUTS: integer time

    output :      gst      greenwich mean sideral time (radians)
                  slong    longitude along ecliptic (radians)
                  sra      right ascension (radians)
                  sdec     declination of the sun (radians)
                  obliq    inclination of Earth's axis (radians)

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[16]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: tgeigse_vect

    Purpose: GEI to GSE transformation
             (vectorized version of tgeigse from ROCOTLIB by
              Patrick Robert)

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[17]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: tgsegei_vect

    Purpose: GSE to GEI transformation
             (vectorized version of tgsegei from ROCOTLIB by
              Patrick Robert)

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[18]

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    procedure: tgsegsm_vect

    Purpose: GSE to GSM transformation
             (vectorized version of tgsegsm from ROCOTLIB by
              Patrick Robert)

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[19]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: tgsmgse_vect

    Purpose: GSM to GSE transformation
             (vectorized version of tgsmgse from ROCOTLIB by
              Patrick Robert)

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[1]

[Previous Routine] [Next Routine] [List of Routines]

    pro sub_GSE2GSM

    Purpose: transforms data from GSE to GSM

    keywords:
       /GSM2GSE : inverse transformation
    Example:
          sub_GSE2GSM,tha_fglc_gse,tha_fglc_gsm

          sub_GSE2GSM,tha_fglc_gsm,tha_fglc_gse,/GSM2GSE

    Notes: under construction!!  will run faster in the near future!!

    Written by Hannes Schwarzl
     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/cotrans_lib.pro $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[20]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: tgsmsm_vect

    Purpose: GSM to SM transformation
             (vectorized version of tgsmsma from ROCOTLIB by
              Patrick Robert)

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[21]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: tsmgsm_vect

    Purpose: SM to GSM transformation
             (vectorized version of tsmagsm from ROCOTLIB by
              Patrick Robert)

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[22]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: cdipdir_vect

    Purpose: calls cdipdir from ROCOTLIB in a vectorized environment

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $

     faster algorithm (for loop across all points avoided) Hannes 05/25/2007

     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[23]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: cdipdir

    Purpose: cdipdir from ROCOTLIB. direction of Earth's magnetic axis in GEO

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[2]

[Previous Routine] [Next Routine] [List of Routines]

    pro: sub_GEI2GSE

    Purpose: transforms THEMIS fluxgate magnetometer data from GEI to GSE

    keywords:
       /GSE2GEI : inverse transformation
    Example:
          sub_GEI2GSE,tha_fglc_gei,tha_fglc_gse

          sub_GEI2GSE,tha_fglc_gse,tha_fglc_gei,/GSE2GEI

    Notes: under construction!!  will run faster in the near future!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[2]

[Previous Routine] [Next Routine] [List of Routines]

    pro sub_GSM2SM

    Purpose: transforms data from GSM to SM

    keywords:
       /SM2GSM : inverse transformation
    Example:
          sub_GSM2SM,tha_fglc_gsm,tha_fglc_sm

          sub_GSM2SM,tha_fglc_sm,tha_fglc_gsm,/SM2GSM

    Notes: under construction!!  will run faster in the near future!!

    Written by Hannes Schwarzl
     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/cotrans_lib.pro $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[3]

[Previous Routine] [Next Routine] [List of Routines]

    pro sub_GEI2GEO

    Purpose: transforms data from GEI to GEO

    keywords:
       /GEO2GEI : inverse transformation
    Example:
          sub_GEI2GEO,tha_fglc_gei,tha_fglc_geo

          sub_GEI2GEO,tha_fglc_geo,tha_fglc_gei,/GEO2GEI

    Notes:

    Written by Patrick Cruce(pcruce@igpp.ucla.edu)
     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/cotrans_lib.pro $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[4]

[Previous Routine] [Next Routine] [List of Routines]

    pro sub_GEO2MAG

    Purpose: transforms data from GEO to MAG

    keywords:
       /MAG2GEO : inverse transformation
    Example:
          sub_GEO2MAG,tha_fglc_geo,tha_fglc_mag

          sub_GEO2MAG,tha_fglc_mag,tha_fglc_geo,/MAG2GEO

    Notes:

    Written by Patrick Cruce(pcruce@igpp.ucla.edu)
     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/cotrans_lib.pro $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[5]

[Previous Routine] [Next Routine] [List of Routines]

    proceddure: subGEI2GSE

    Purpose: transforms data from GEI to GSE

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!  will run faster in the near future!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[6]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: subGSE2GEI

    Purpose: transforms data from GSE to GEI

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!  will run faster in the near future!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[7]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: subGSE2GSM

    Purpose: transforms data from GSE to GSM

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!  will run faster in the near future!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[8]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: subGSM2GSE

    Purpose: transforms data from GSM to GSE

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!  will run faster in the near future!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_LIB[9]

[Previous Routine] [Next Routine] [List of Routines]

    procedure: subGSM2SM

    Purpose: transforms data from GSM to SM

    INPUTS: TIMES as time_struct, DATA_in as nx3 array

    keywords:

    Example:

    Notes: under construction!!

     $LastChangedBy: crussell $
     $LastChangedDate: 2012-04-17 08:52:44 -0700 (Tue, 17 Apr 2012) $
     $LastChangedRevision: 10337 $
     $URL $

(See ssl_general/cotrans/cotrans_lib.pro)

## COTRANS_SET_COORD

[Previous Routine] [Next Routine] [List of Routines]

    	Function: COTRANS_SET_COORD

    	Purpose:  set the coordinate system of data by
                     setting the data_att structure of its DLIMIT structure.

    	Calling Sequence:
    		tplot_var = 'tha_eff'
    		get_data, tplot_var, data=d, limit=l, dlimit=dl
    		coord = cotrans_set_coord, dl, 'gei'
    		store_data, tplot_var, data=d, limit=l, dlimit=dl

    	Arguements:
    		DL, Anonymous STRUCT.

    	Notes:
    		None.

     $LastChangedBy: kenb-mac $
     $LastChangedDate: 2007-08-01 22:08:30 -0700 (Wed, 01 Aug 2007) $
     $LastChangedRevision: 1318 $
     $URL $

(See ssl_general/cotrans/cotrans_set_coord.pro)

## GEO2MAG

[Previous Routine] [Next Routine] [List of Routines]

     NAME:
           geo2mag

     PURPOSE:
           Convert from geographic to geomagnetic coordinates

     CALLING SEQUENCE:
           geo2mag, time, data_in, data_out

     INPUT:
           time = an array [n] of double precision time in seconds from 1970-Jan-01/00:00:00.000
           data_in = an array [n,3] of position data in km. in GEO coordinates or a tplot variable

     KEYWORD INPUTS:
           None

     OUTPUT:
           data_out = an array [n,3] of the input data in MAG coordinates

     EXAMPLE:

           IDL> geo2mag, data_in data_out

     NOTES:

           The algorithm and rotational matrices were developed by Pascal Saint-Hilaire
           (Saint-Hilaire@astro.phys.ethz.ch), May 2002

     MODIFICATION HISTORY:

(See ssl_general/cotrans/geo2mag.pro)

## HDZ2GEO

[Previous Routine] [Next Routine] [List of Routines]

    procedure: hdz2geo

    Purpose: Coordinate transformation between HDZ coordinates & GEO coordinates

         HDZ is defined as:

           H = horizontal field strength, in the plane formed by Z and GEO graphic north
           D = field strength in the Z x X direction in nT
           Z = downward field strength

         H should be a projection onto a basis vector pointing north from station in nT
         D should be a projection onto a basis vector perpendicular to H in the horizontal plane.

         Total field strength should be sqrt(H^2+D^2+Z^2) not sqrt(H^2+Z^2)
         D must be in nT not degrees

         GEO is defined as:
             X = Vector parallel to vector pointing outward at the intersection of the equatorial plane and the 0 degree longitudinal meridean(Greenwich Meridean)
             Y = Z x X
             Z = Vector parallel to orbital Axis of Earth Pointing northward.

    inputs:

      data_in:
        Name of input tplot variable to be transformed, or Nx3 array of data for transformation. If no tplot variable is specific latitude and longitude must be set.
      data_out:
        Name of tplot variable in which to store output.  If this is a named variable and not a string, output data will instead be returned in variable.
      latitude: latitude of the HDZ station, must be set if data_in is not tplot variable, or latitude and longitude not stored in dlimit.data_att or dlimit.cdf.vatt
      longitude: longitude of the HDZ station, must be set if data_in is not tplot variable, or latitude and longitude not stored in dlimit.data_att or dlimit.cdf.vatt
      geo2hdz: If set, performs inverse transformation from GEO to HDZ
      error: Set to named variable that will return 1 if an error occurs and 0 otherwise
      rotation_matrix:  Returns the rotation matrix that will be used to transform

    keywords:

       /SSE2GSE inverse transformation

       /IGNORE_DLIMITS: Dlimits normally used to determine if coordinate
       system is correct, to decide if position needs offset, or to
       stop incorrect transforms.  This option will stop this behavior.

    Examples:
      hdz2geo,hdz_arr_in,geo_arr_out,latitude=60.4,longitude=173.6
      hdz2geo,'in_tvar_name_hdz','out_tvar_name_geo'
      hdz2geo,'in_tvar_name_geo','out_tvar_name_hdz',/geo2hdz  ;inverse transformation

    Notes:
       #1 HDZ coordinates only make sense relative to a location, assumedly a ground station(gmag)

       #2 Specific latitude and longitude keywords must be set if:
        (1) data_in is not a tplot variable name
        -OR-
        (2) tplot variable named by data_in does not specific site_latitude & site_longitude in dlimits

       #3 If latitude or longitude keywords are set, these values will be used, not dlimit values.

       #4 This transformation is a first order approximation.  It treats the earth as if it is a true sphere, ignoring
       distortions due to the fact that the earth is actually an oblate spheroid.

       Written by Patrick Cruce(pcruce@igpp.ucla.edu)

     $LastChangedBy: pcruce $
     $LastChangedDate: 2010-03-29 15:27:35 -0700 (Mon, 29 Mar 2010) $
     $LastChangedRevision: 7445 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/hdz2geo.pro $

(See ssl_general/cotrans/hdz2geo.pro)

## MAG2GEO.PRO

[Previous Routine] [Next Routine] [List of Routines]

     NAME:
          mag2geo.pro

     PURPOSE:
         Convert from geomagnetic to geographic coordinates

     CALLING SEQUENCE:
           mag2geo, time, data_in, data_out

     INPUT:
           data_in = an [n,3] element array of position data in km and in
                    MAG coordinates

     KEYWORD INPUTS:
                   None

     OUTPUT:
           data_in = an [n,3] element array of position data in km in
                     newly transformed GEO coordinates

     EXAMPLE:

           IDL> geo2mag, data_in data_out

     NOTES:

           The algorithm and rotational matrices were developed by Pascal Saint-Hilaire
           (Saint-Hilaire@astro.phys.ethz.ch), May 2002

     MODIFICATION HISTORY:

(See ssl_general/cotrans/mag2geo.pro)

## SPG2SSL

[Previous Routine] [List of Routines]

    procedure: spg2ssl

    Purpose: coordinate transformation

             SPG<-->SSL;

    inputs

    	name_thx_xxx_in 	... data in the input coordinate system (t-plot variable name)
       name_thx_xxx_out    ... name for output  (t-plot variable name)

    keywords:
       TRANSFORMATIONS

       /SSL2SPG inverse transformation

       /IGNORE_DLIMITS if the specified from coord is different from the
    coord system labeled in the dlimits structure of the tplot variable
    setting this keyword prevents an error

    Example:
          spg2ssl,'tha_fgl_spg','tha_fgl_ssl'
          spg2ssl,'tha_fgl_ssl','tha_fgl_spg',/SSL2SPG
    Notes: under construction!!

    Written by Hannes Schwarzl
     $LastChangedBy: kenb-mac $
     $LastChangedDate: 2007-05-05 10:29:05Z $
     $LastChangedRevision: 645 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/ssl2dsl.pro $

(See ssl_general/cotrans/spg2ssl.pro)