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HELP FOR: grmap
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CALLING SEQUENCE: grmap ( objects, function, arg1, arg2,...)

      PARAMETERS: objects  - GRTensorII object name or sequence of object names
                  function - name of a procedure
                  arg1..n  - arguments for function (one of which must be 'x' )

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SYNOPSIS:

- Applies MapleV function to each component of the GRTensorII objects
  specified.

- The function which is applied may take any number of arguments. These
  are specified by the arguments `arg1', `arg2', etc., to grmap().
  The argument which is to hold the tensor component is indicated by the
  place-holder 'x'. For example, the MapleV subs function is usually
  invoked as

                       subs ( r=2*m, a=0.1, f(r,a) ):

  If we wished to apply this same substitution to each component of the
  covariant Ricci tensor we could use the following grmap command:

                 grmap ( R(dn,dn), subs, r=2*m, a=0.1, 'x' ):

- Note that for functions of only one variable, the command gralter() can
  also be used with equivalent results.

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EXAMPLES:

# apply the routine normal() to the Riemann tensor
> grmap ( R(dn,dn,dn,dn), normal, 'x' ):

# perform taylor expansion to third order about r=a
> grmap ( R(dn,dn,dn,dn), taylor, 'x', r=a, 2):

# substitute m=5 in Riemann and Weyl
> grmap ( R(dn,dn,dn,dn), C(dn,dn,dn,dn), subs, m=5, 'x' ):

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SEE ALSO:  gralter, map, grcalc, grt_objects.
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