Monday, January 28, 2008

Plotting implicit functions: a bleg..

Does anyone know of good tools for plotting implicit functions ? Ideally, I'd like something that could plot functions of the form f(x,y) = 0, and even contours of the form f(x,y) = c.

(for those who aren't hip with web jargon, a bleg is a beg on a blog ;)



    If you eventually want 3D contours, then VTK should do the job.

  2. If you are OK with commercial tools, Mathematica's ContourPlot does it

  3. I'd go with surf

    It lets you plot implicit curves and surfaces, and does a surprisingly good job of it. Main drawback: it only takes algebraic specifications (i.e. f needs to be a polynomial), and it doesn't have comfortable rotation and zooming.

    Mouse grab-and-pull rotation and zooming has been added to the surfer extension GUI

  4. ah that's the problem. my function has logs in it. But some of the other options seem doable.

  5. Maple does it with implicitplot()

    Not sure how great it is though...

  6. Grapher (comes with every mac) seems to work pretty well. I tried plotting log(xy) = 1.


  7. What an opportunity to advertize our tool ;-) (for algebraic curves only)

    You can try it online with our browser

  8. Can't you just take g(x,y) = f(x,y)-c ?

  9. Try TexasInstruments T-98 thay are compact for travel and you can usually buy them used;via. pawn shops, consignment shops, etc....

  10. With a little wiggling, the common and freely available gnuplot can do this:

  11. MATLAB has the command contour and isosurf.

    Amusingly grapher the OS X utility also plots implicits via extracting isosurfaces (or curves / contour lines).

  12. Jonathan Thornburg7/30/2011 09:56:00 AM

    I second the recommendation of gnuplot
    (; alas the .org seems to be owned by a domain squatter).
    It has excellent support for parametric functions (x = x(t,u), y = y(t,u), z = z(t,u)), and reasonable support for both 2-D and 3-D contours.

  13. I used the free software available here
    It has a utility called "relation" in which you may define functions of the form f(x,y)= C. It is meant for windows but I installed it just fine on Ubuntu-9.04 using wine. Works great.



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