gnuplot-info

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

[Sekiryou <sek...@gm...>]

Hi, i need to plot a function and make it rotate around an axis in a 3D.
Example:
   I have the function f(x)=x^2 and i need to rotate it around the y axis.

Is there a way to do that with Gnuplot?

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

[<HBB...@t-...>]

Sekiryou wrote:
> Hi, i need to plot a function and make it rotate around an axis in a 3D.
> Example:
>    I have the function f(x)=x^2 and i need to rotate it around the y axis.

splot (x**2+y**2)

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

[Sekiryou <sek...@gm...>]

Hans-Bernhard Br=C3=B6ker-2 wrote:
> splot (x**2+y**2)

It's not really what i'm expecting... in fact the command you gave me,
doesn't rotate around the y axis...=20
What i want is more like the image i attach here.

http://www.nabble.com/file/8163/rotation.gif=20
--=20
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Re: [Gnuplot-info] make a function rotate around an axis

[<HBB...@t-...>]

Sekiryou wrote:
> 
> 
> Hans-Bernhard Bröker-2 wrote:
>> splot (x**2+y**2)
> 
> It's not really what i'm expecting... in fact the command you gave me,
> doesn't rotate around the y axis... 

It does --- it's just a bit harder to see.

But if you insist on a round outline:

	set parametric
	set urange [0:5]
	set vrange [0:2*pi]
	splot u*cos(v), u*sin(v), u**2

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

[Sekiryou <sek...@gm...>]

Seems a bit complicated...=20

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.


Hans-Bernhard Br=C3=B6ker-2 wrote:
>=20
> Sekiryou wrote:
>>=20
>>=20
>> Hans-Bernhard Br=C3=B6ker-2 wrote:
>>> splot (x**2+y**2)
>>=20
>> It's not really what i'm expecting... in fact the command you gave me,
>> doesn't rotate around the y axis...=20
>=20
> It does --- it's just a bit harder to see.
>=20
> But if you insist on a round outline:
>=20
> =09set parametric
> =09set urange [0:5]
> =09set vrange [0:2*pi]
> =09splot u*cos(v), u*sin(v), u**2

--=20
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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

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

[<HBB...@t-...>]

Sekiryou wrote:
> Seems a bit complicated... 

Appearances can be deceptive.

> 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.

And what do you expect to get in the way of doing that?

> I think it will be hard to do like you show me.

Any attempt to display a solid volume on a 2D screen is hard.  That's the