       [no subject]

• To: mathgroup at yoda.physics.unc.edu
• From: twj
• Date: Fri, 7 Aug 92 14:10:02 CDT

```In reply to  Simon Chandler <simonc at hpcpbla.bri.hp.com>

>This does indeed plot a surface, however, there are two problems.

>1.  If the x and y values have different magnitudes the bounding box
>    for the surface is long and skinny.  There does not seem to be any
>    automatic scaling of the axes or any options to control the axes.

This is exactly what the option BoxRatios does.   You are (probably)
using the setting BoxRatios -> Automatic,   use BoxRatios -> {1,1,1}
for a cubical box.   BoxRatios acts in an analogous fashion in
three-dimensions to the way AspectRatio acts in two-dimensions.

>2.  The axes of the plot are not numbered so one cannot tell the
>    values of x and y from the plot.  This rules out use of this function
>    to present experimental data where calibrated axes are essential.
>    Even ListPlot3D of data with reqularly spaced x and y values does
>    not allow one to calibrate the axes - the plot's axes are always
>    numbered with the array's row and column numbers.

NO, if you use ListSurfacePlot3D you can set Axes and they will just
work properly.  Thus

In:= <<Graphics/Graphics3D.m

In:= apts = Table[ {Cos[t] Cos[ u], Sin[t] Cos[ u], Sin[u]},
{t,0,Pi, Pi/5}, {u,0,Pi/2, Pi/10}];

In:= ListSurfacePlot3D[ apts]

Out= -Graphics3D-

In:= Show[ %, Axes -> True]

Out= -Graphics3D-

You can't just do ListSurfacePlot3D[ apts, Axes -> True] because of
a bug in the Graphics3D.m package definition for ListSurfacePlot3D
which IS fixed in V2.1  The code leaves no optional pattern for
options to pass on.

If you do ListPlot3D then if you want to get the axes scaled properly
you must set the MeshRange option.   This is just set to be the
min and max values in x and y.   Thus if your data goes from -5 to 5
in both x and y you would do

ListPlot3D[ data, MeshRange -> {{xmin, xmax}, {ymin, ymax}}]

It needs this information since the first argument only contains the
heights of the function.   You can look at the output of Plot3D
with InputForm to see exactly what the thing should look like.

Tom Wickham-Jones
WRI

```

• Prev by Date: Timing of a simple table operation
• Next by Date: MMA/postscript/Textures
• Previous by thread: Timing of a simple table operation