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HELP FOR: Info
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SYNOPSIS:

 - The `Info' object stores the text description of metrics and bases loaded
   via qload() (or grload()). 

 - The contents of this variable can be displayed via grdisplay() or altered
   using grcalc(), in which case the user is prompted to type a new line of 
   text. [To change the value of the Info variable, remember to use
   grclear() to clear its value before using grcalc().]

 - Alterations to the Info variable can be saved using grsaveg() so that it
   is retained for the next session using the same metric file.

 - In metric files, the Info string is read from the variable Info_. This
   variable can be modified using a text editor.

 - The Info variable in metric files can be used to provide a convenient
   listing of metrics using certain system-specific utilities external to
   MapleV. For instance, from a metric directory, the following Unix
   command will list the Info line for each metric in the directory:

    % grep Info_ *.mpl
       .
       .
       .
     planewave.mpl:Info_ := `    Plane wave metric.    `: 
     planewavempl.mpl:Info_ := `    The plane wave metric.    `: 
     rw.mpl:Info_:= ` Robertson-Walker Metric `:
     schmidt1.mpl:Info_ := `    A metric for which all curvature invariants 
      vanish    `: 
     schw.mpl:Info_:=`The Classical Schwarzschild metric`:
     schwb.mpl:Info_ := `    Schwarzschild orthonormal basis   `: 
     schwl.mpl:Info_:` Schwarzschild Metric with Lambda `:
     schwx.mpl:Info_ := `    The Classical Schwarzschild metric    `: 
     shw.mpl:Info_ := `    
     ss.mpl:Info_ := `    Metric for the general homothetic spherical space
      time.    `: 
     ss1.mpl:Info_ := `    Self-similar metric "curvature form"    `: 
     ss2.mpl:Info_ := `    Self-similar metric "comoving form"    `: 
     ss3.mpl:Info_ := `    Self-similar metric "Bondi form"    `: 
     tb.mpl:Info_ := `    Tolman-Bondi, no constraints.    `: 
       .
       .
       .
      etc.

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EXAMPLE:

> qload ( rw ):

> grdisplay ( Info ):
 
                             For the rw spacetime:
 
                  Text description  = Robertson-Walker Metric
 
> grclear ( Info ):
Cleared Info for the rw metric.

> grcalc ( Info ):

Enter text information:

 Friedmann-Lemaitre-Robertson-Walker metric
 
> grsaveg ( flrw ):
Information written to: /home/grtensor/metrics/flrw.mpl

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SEE ALSO:  makeg, grsaveg, grclear.
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