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

[Amir S. <ami...@gm...>]

Hi Jody, it worked perfectly. Thank you also for the math lesson :-)

Amir

On 20 April 2011 17:35, Amir Sabbagh <ami...@gm...> wrote:

> Thank you so much  Jody, tomorrow I'll try it.
>
>
> On 20 April 2011 17:22, jody <jod...@gm...> wrote:
>
>> HI Amir
>>
>> if your plane equation is p*x + q*y +r*z + d = 0,
>> then two orthogonal vectors in your plane are for example a=(q, -p, 0)
>> and b=(p*r, q*r, -(p^2+q^2))
>> Usually it is a good idea to scale those vectors to unit length
>>
>> Jody
>>
>>
>> On Wed, Apr 20, 2011 at 5:13 PM, jody <jod...@gm...> wrote:
>> > 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
>> >> **************************************************************
>> >>
>> >>
>> >
>>
>
>
>
> --
> **************************************************************
> Amir Sabbagh
> Il mio sito / My site: http://almucantarat.altervista.org
> **************************************************************
>
>


-- 
**************************************************************
Amir Sabbagh
Il mio sito / My site: http://almucantarat.altervista.org
**************************************************************