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# Directory Listing of Routines

# ssl_general/cotrans/special

- TCROSSP
- TDOTP
- TINTERPOL_MXN
- TNORMALIZE
- TVECTOR_ROTATE

# Routine Descriptions

## TCROSSP

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    PROCEDURE: TCROSSP
    Purpose:
      Vectorized routine to calculate the cross product of two tplot
      variables containing arrays of 3d vectors and storing the result
      in a tplot variable

    Arguments:
     v1: The name of the tplot variable storing the first vector in the cross product
     v2: The name of the tplot variable storing the second vector in the
     cross product

     newname(optional): the name of the output tplot variable

     error(optional): named variable in which to return error state of
     the computation.  1 = success 0 = failure

    NOTES:

(See ssl_general/cotrans/special/tcrossp.pro)

## TDOTP

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    PROCEDURE: TDOTP
    Purpose:
      Vectorized routine to calculate the dot product of two tplot
      variables containing arrays of vectors and storing the results
      in a tplot variable

    Arguments:
     v1: The name of the tplot variable storing the first vector in the dot product
     v2: The name of the tplot variable storing the second vector in the
     dot product

     newname(optional): the name of the output tplot variable

     error(optional): named variable in which to return the error state
     of the computation.  1 = success 0 = failure

    NOTES:

(See ssl_general/cotrans/special/tdotp.pro)

## TINTERPOL_MXN

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    Function: tinterpol_mxn

    Purpose:  Generalized interpolates across a series of vectors(since
    interpol only works on 1-d vectors) This function works on any
    n-dimensional vectors. Basically, this is an element by element
    interpolation across M

     - i. works on tplot variables
         - ii. allows no extrapolation beyond valid data with
              /no_extrapolate keyword"

    Arguments:
                xv_tvar = tplot variable to be interpolated, the y component
                can have any dimesions, can use globbing to interpolate
                many values at once
                uses x component for x abcissa values

                uz_tvar = tplot variable that V will be fit to
                uses x component for u abcissa values.  Can also
                pass in an array of time values rather than a tplot
                variable.

                newname = output variable name(optional) defaults to
                xv_tvar+'_interp'

                suffix = a suffix other than interp you can use,
                particularily useful when using globbing

                overwrite=set this variable if you just want
                the original variable overwritten instead of using
                newname or suffix

                Use only newname or suffix or overwrite. If you combine
                them the naming behavior may be erratic

                /LINEAR = pass this argument to specify linear
                interpolation(this is the default behavior)

                /QUADRATIC = pass this argument to specify quadratic
                interpolation

                /SPLINE = pass this argument to specify spline
                interpolation

                /NO_EXTRAPOLATE = pass this argument to prevent
                extrapolation of data values in V passed it's start and
                end points

                /NAN_EXTRAPOLATE = pass this argument to extrapolate past
                the endpoints using NaNs as a fill value

                ERROR(optional): named variable in which to return the error state
                of the computation.  1 = success 0 = failure

    CALLING SEQUENCE;
               tinterpol_mxn,'tplot_var1','tplot_var2',out_var='tplot_var_out'
               tinterpol_mxn,'tplot_var1','tplot_var2',/NO_EXTRAPOLATE
               tinterpol_mxn,'tplot_var1','tplot_var2',/SPLINE

    Output: an N by D1 by D2 by ... array stored in an output tplot variabel

    Notes:
    Uses a for loop over D1*D2*..., but I'm operating under the assumption that
    D1*D2... << M (D1 * D2 *... is waaaay less than M)

    It uses a little bit of modular arithmatic so this function is
    generalized to any array dimensionality(IDL limits at 8)

    Examples:
     if the input is an array of 3-d vectors(say 1,1,1 and 2,2,2) and we
     want 3 vectors out the output is 1,1,1 1.5 1.5 1.5 2,2,2
     if the input is an array of 3x3 matrices(say all ones and all twos)
     and we want three matrices then output is all 1s all 1.5s all 2s

     $LastChangedBy: pcruce $
     $LastChangedDate: 2008-12-05 09:42:42 -0800 (Fri, 05 Dec 2008) $
     $LastChangedRevision: 4106 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/special/tinterpol_mxn.pro $

(See ssl_general/cotrans/special/tinterpol_mxn.pro)

## TNORMALIZE

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    PROCEDURE: TNORMALIZE
    Purpose:
      Vectorized routine to normalize all the vectors stored in a tplot
      variable

    Arguments:
     v: The name of the tplot variable storing the vectors to be
     normalized
     newname(optional): The name of the output tplot variable. Defaults
     to v+'_normalized'
     error(optional): Named variable in which to return the error state
     of the computation, 1 = success, 0 = failure

    NOTES:

     $LastChangedBy: bckerr $
     $LastChangedDate: 2008-07-31 16:52:00 -0700 (Thu, 31 Jul 2008) $
     $LastChangedRevision: 3322 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/special/tnormalize.pro $

(See ssl_general/cotrans/special/tnormalize.pro)

## TVECTOR_ROTATE

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    Procedure: tvector_rotate

    Purpose:  rotates a set of vectors by a set of coordinate
              transformation matrices inputs and outputs are tplot
              variables.  This is designed mainly for use with
              fac_matrix_make.pro and minvar_matrix_make, but can be used
              for more general purposes

    Warning:
     The transformation matrices generated by
    fac_matrix_make,thm_fac_matrix_make, and minvar_matrix_make are
    defined relative to a specific coordinate system.  This means that if
    you use vectors in one coordinate system to generate the rotation
    matrices they will only correctly transform data from that coordinate
    system into the functional coordinate system.  For example if you use
    magnetic field data in gsm to generate Rgeo transformation matrices
    using fac_matrix_make then the vectors being provided to tvector
    rotate to be transformed by those matrices should only be in gsm coordinates.

    Arguments:

     mat_var_in: the name of the tplot variable storing input matrices
     The y component of the tplot variable's data struct should be
     an Mx3x3 array, storing a list of transformation matrices.

     vec_var_in: the name of the tplot variable storing input
    vectors. You can use globbing to rotate several tplot variables
    storing vectors with a single matrix. The y component of the tplot variable's
     data struct should be an Nx3 array.

     newname(optional): the name of the output variable, defaults to
                        vec_var_in + '_rot'
                        If you use type globbing in the vector variable
                        This option will be disabled

     error(optional): named variable in which to return the error state
     of the computation.  1 = success 0 = failure

    CALLING SEQUENCE:

     tvector_rotate,'matrix_var','vector_var',newname = 'out_var',error=error

     tvector_rotate,'matrix_var','vector_var'

    Notes:
       mat_var_in should store rotation matrices.  (ie the columns of any
       matrix in mat_var_in should form an orthonormal basis)

       If M!=N M must be >= 2 (where M,N refer to the dimensions of the
       input variables.

       Also If the x components of mat_var_in and vec_var_in data structs
       do not match then. The matrices will be interpolated to match the
       cadence of the vector data.  Interpolation is done by turning the
       matrices into quaternions and performing spherical linear
       interpolation.  As noted above this interpolation behavior will
       not be predictable if the matrices do anything other than rotate.

       The user should note that if the timestamps of mat_var_in are not
       monotonic(ascending or identical) or if the timestamps vec_var_in are not strictly
       monotonic(always ascending) the program will not work correctly.  It is the user's
       responsibility to remove duplicate or non sequential timestamps from the data

       PROGRAMMERS: you might want to consider adding a check to
       verify that input matrices are actually rotation matrices
       this would just verify that M dot transpose(M) = Identity matrix

     SEE ALSO:  mva_matrix_make.pro, fac_matrix_make.pro

     $LastChangedBy: jimm $
     $LastChangedDate: 2008-05-13 16:54:59 -0700 (Tue, 13 May 2008) $
     $LastChangedRevision: 3076 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/ssl_general/trunk/cotrans/special/tvector_rotate.pro $

(See ssl_general/cotrans/special/tvector_rotate.pro)