## gnuplot-info

 [Gnuplot-info] Cone in parametric :-) From: Carles Pina i Estany - 2007-01-17 18:09:37 ```Hello, I am not able to plot cylinder using cartesian system (I think that is not possible in gnuplot?) I am trying to do the figures that I need using parametric coordinate. I have done without problemes sphere, cylinder but I need cone. Here for example: http://mathworld.wolfram.com/Cone.html There is the parametric equations (equations number 1, 2 and 3). I do in gnuplot: set parametric set isosample 51 set ticslevel 0 h=2.0 r=1.0 splot ((h-u)/h)*r*cos(u), ((h-u)/h)*r*sin(u),v pause -1 And something appears but doesn't look as a cone :-) Any idea? the formula seems correct, Maybe range problem for u and v? Thank you very much, -- Carles Pina i Estany GPG id: 0x8CBDAE64 http://pinux.info Manresa - Barcelona ```
 Re: [Gnuplot-info] Cone in parametric :-) From: - 2007-01-18 22:10:53 ```Carles Pina i Estany wrote: > Hello, > > I am not able to plot cylinder using cartesian system (I think that is > not possible in gnuplot?) You think incorrectly. > I am trying to do the figures that I need using parametric coordinate. You're confusing things here. There's no such thing as "parametric coordinates". Parametric is a model for describing surfaces, not a coordinate system. Gnuplot does parametric plots in a cartesian coordinate system. A simple cylinder is set parametric set urange [0:2*pi]; set vrange [-2:2] splot cos(u), sin(u), v title "cylinder" > Any idea? the formula seems correct, Maybe range problem for u and v? Quite certainly, since you didn't specify any ranges for u and v. Please do read the documentation: "help parametric". ```
 Re: [Gnuplot-info] Cone in parametric :-) From: Carles Pina i Estany - 2007-01-19 20:04:47 ```Hi, On Jan/18/2007, Hans-Bernhard Br=F6ker wrote: > >I am trying to do the figures that I need using parametric coordinate.= =20 >=20 > You're confusing things here. There's no such thing as "parametric=20 > coordinates". Parametric is a model for describing surfaces, not a=20 correct, I was confusing it. My blame > coordinate system. Gnuplot does parametric plots in a cartesian=20 > coordinate system. A simple cylinder is >=20 > set parametric > set urange [0:2*pi]; set vrange [-2:2] > splot cos(u), sin(u), v title "cylinder" iep, it works (of course). Now I can do my figures in two ways :-) Thanks! > >Any idea? the formula seems correct, Maybe range problem for u and v? >=20 > Quite certainly, since you didn't specify any ranges for u and v.=20 > Please do read the documentation: "help parametric". I was in hurry and I miss-understood, now is fine! Sorry for the stupid mistakes: error with u and v in some formula, divide two integers and expect a float and this... --=20 Carles Pina i Estany GPG id: 0x8CBDAE64 http://pinux.info Manresa - Barcelona ```

No, thanks