Re: [Gnuplot-info] plot 2D circle in 3D graph

[jody <jod...@gm...>]

Hi Amir

To display the plane you have to find its parametric description, i.e.
x = a1*u+b1*v+c1
y = a2*u+b2*v+c2
z = a3*u+b3*v+c3

in other words, you have to find two vectors a=(a1, a2, a3) and b=(b1, b2, b3)
spanning your plane, as well as the offset c=(c1,c2,c3)

then you can plot your plane like that

  splot [u=-5:5] [v=-5:5] a1*u+b1*v+c1, a2*u+b2*v+c2, a3*u+b3*v+c3

simple example
  x = u
  y = v
  z = 3

the you plot it lie this:

  splot [u=-5:5] [v=-5:5] u, v, 3

Jody


On Wed, Apr 20, 2011 at 4:22 PM, Amir Sabbagh <ami...@gm...> wrote:
> Hi Jody,
> thank you very much for the answer, it helped a lot.
> is it possible to dispklay both the circle and the plane?
>
> On 20 April 2011 13:52, jody <jod...@gm...> wrote:
>>
>> Hi Amir
>>
>> Yes. For patametric curves you first have to type
>>
>>  set parametric
>>
>> next set your constants
>>  R=5
>>  d=4
>>  e=6
>>  c=15
>>
>> and then do the plotting (splot is for 3d plots)
>>  splot [t=0:2*pi]  d+R*cos(t), e+R*sin(t),c
>>
>> Hope this helps
>> Jody
>>
>> On Wed, Apr 20, 2011 at 12:28 PM, Amir Sabbagh <ami...@gm...> wrote:
>> > Thank you Jody for the tip. The problem with this option is that I get a
>> > "undefined variable: t" error when I try to splot it.
>> > Maybe there is a workaround for this?
>> >
>> > Amir
>> >
>> > On 20 April 2011 12:00, jody <jod...@gm...> wrote:
>> >>
>> >> Hi Amir
>> >>
>> >> You could try a parametric version of your circle:
>> >>  x = d+R*cos(t)
>> >>  y = e+R*sin(t)
>> >>  z = k
>> >>
>> >> This gives you a horizontal circle centered at (d,e,k)
>> >> For a tilted circle you would have to apply rotations
>> >> around the x and/or y axis.
>> >>
>> >> Jody
>> >>
>> >>
>> >> On Wed, Apr 20, 2011 at 11:36 AM, Amir Sabbagh <ami...@gm...>
>> >> wrote:
>> >> > Hi you all,
>> >> >
>> >> > I am trying to plot a circle and a plane with splot.
>> >> >
>> >> > I would like to have a circle at a Z=const value. I have tryed with
>> >> > ternary
>> >> > operation with no success.
>> >> >
>> >> >   splot a*x+b*y+c title "Plane", \
>> >> >   (x-d)**2 + (y-e)**2 - R**2==0? ((x-d)**2 + (y-e)**2 - R**2): 0/0
>> >> > with
>> >> > title "Circle"
>> >> >
>> >> > Can someone enlight me?
>> >> >
>> >> > Thank you
>> >> > Amir
>> >> >
>> >> >
>> >> > --
>> >> > **************************************************************
>> >> > Amir Sabbagh
>> >> > Il mio sito / My site: http://almucantarat.altervista.org
>> >> > **************************************************************
>> >> >
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>> > --
>> > **************************************************************
>> > Amir Sabbagh
>> > Il mio sito / My site: http://almucantarat.altervista.org
>> > **************************************************************
>> >
>> >
>
>
>
> --
> **************************************************************
> Amir Sabbagh
> Il mio sito / My site: http://almucantarat.altervista.org
> **************************************************************
>
>