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(gnuplot.info)mapping

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Enter node , (file) or (file)node

 If data are provided to `splot` (Note: splot ) in spherical or cylindrical
 coordinates, the `set mapping` command should be used to instruct `gnuplot`
 (Note: gnuplot ) how to interpret them.

 Syntax:
       set mapping {cartesian | spherical | cylindrical}

 A cartesian coordinate system is used by default.

 For a spherical coordinate system, the data occupy two or three columns (or
 `using` (Note: using ) entries).  The first two are interpreted as the polar
 and azimuthal angles theta and phi (in the units specified by `set angles`
 (Note: angles )).  The radius r is taken from the third column if there is
 one, or is set to unity if there is no third column.  The mapping is:

       x = r * cos(theta) * cos(phi)
       y = r * sin(theta) * cos(phi)
       z = r * sin(phi)

 Note that this is a "geographic" spherical system, rather than a "polar" one.

 For a cylindrical coordinate system, the data again occupy two or three
 columns.  The first two are interpreted as theta (in the units specified by
 `set angles`) and z.  The radius is either taken from the third column or set
 to unity, as in the spherical case.  The mapping is:

       x = r * cos(theta)
       y = r * sin(theta)
       z = z

 The effects of `mapping` can be duplicated with the `using` filter on the
 `splot` command, but `mapping` may be more convenient if many data files are
 to be processed.  However even if `mapping` is used, `using` may still be
 necessary if the data in the file are not in the required order.

 `mapping` has no effect on `plot` (Note: plot ).