===============================================================================
HELP FOR: grcomponent
===============================================================================

CALLING SEQUENCE:  grcomponent ( object, indexList );

      PARAMETERS:  object      - a GRTensorII object name
                   indexList   - index list specifying the component

-------------------------------------------------------------------------------
SYNOPSIS:

- This function can be used to access individual components of tensors.

- The main use of this function is to allow you to assign individual
  components of tensors to functions so that they can be manipulated
  independently.

- The number of entries in the index list must match the number
  of indices of the tensor specified as object. The elements of
  the list may be either coordinate numbers or coordinate names.

- For scalars the indexList is omitted, or an empty list is used.

- The default metric is assumed, however an alternate metric can be
  specified as a parameter to the object name argument, eg.

    > grcomponent ( R[schw](dn,dn,dn,dn), [1,1,1,1] ):

  This command will display the [1,1,1,1] component of the schw metric
  even if this is not the current default.

-------------------------------------------------------------------------------
EXAMPLES:

> qload ( schw ):
> grcalc ( RiemSq ):
> grcomponent ( Chr(dn,dn,up), [theta,theta,r] );

                                   - r

> grcomponent( Chr[schw](dn,dn,up), [2,2,1] ); # equivalent to the previous
                                               # command
                                   - r

> K := grcomponent(RiemSq);
                                          2
                                      48 m
                               K :=   ------
                                         6
                                        r
-------------------------------------------------------------------------------
SEE ALSO: grarray, grdisplay.
===============================================================================