Re: [Gnuplot-info] make a function rotate around an axis

[Lars H. <la...@ho...>]

> Seems a bit complicated...
>
> The purpose of doing that is that i need a picture to
> show the surface it makes. After that we will add another
> function and try to calculate the volume that intersect
> the 2 functions.
>
> I think it will be hard to do like you show me.

If I get you right, you desire a rotational solid and you 
want it to be drawn automatically, if you provide only the 
mathematical function for the borderline. 

gnuplot is only a plotting programme, not able to to the 
calculations needed for a rather complex gemometrical thing 
like a rotational solid. You might "cut" the solid into 
slices, so that you get a bunch of circles, but that won't 
result in a surface.

If you insist in using gnuplot for your task, I would 
suggest, that you use an external programme, which somehow 
calculates the borderline points of the rotational solid in 
3D coordinates and writes it to a tabular in a file. Then 
you could use gnuplot for plotting something similar to 
this: 
  http://gnuplot.sourceforge.net/demo_4.2/surface1.19.png
(see the demos for more details)

Since we're touching the borders of gnuplots facilities with 
this, it may be better to use another (commercial) 
programme, e.g. maple or matlab.

HTH
Lars