Hello all !

I'm sorry if my question is not clear, but I do not know ho to produce a simple example.

I'm plotting the graph of an implicit given function (say x^2+y^2=3) using Sage.

What I know it that

1. when I ask sage to plot implicit_plot( f==3,(x,-5,5),(y,-5,5) ),

Sage computes f-3 on an array of points in the square (-5,-5)x(5,5).

2. Sage creates an object matplotlib.figure.Figure that contains somewhere the information about the array of computed points and ask matplotlib to plot it

What I understood is that somewhere in matplotlib, the values are parsed and a path is created. That path is the set of points on which f-3=0

My aim : catch the set of points that satisfy f-3=0. That has to be stored --or at last computed-- somewhere in matplotlib.figure.Figure

I read the source, but I'm really lost.

The final purpose is to know the bounding box of the points that are *actually* plotted without taking into account the axes, labels and other decorations.

Does someone know how to do that ?

Since the object I have on hand is created by Sage[1] in a quite complex way, I'm sorry to not being able to furnish an example.

Thanks

Laurent

If it can help, I have the following in a Sage terminal :

sage: var('x,y')

sage: F=implicit_plot(x**2+y**2==2,(x,-5,5),(y,-5,5),plot_points=100)

sage: F.matplotlib()

<matplotlib.figure.Figure object at 0xbfb60ac>

sage: F.matplotlib().get_children()

[<matplotlib.patches.Rectangle object at 0xc144e4c>, <matplotlib.axes.AxesSubplot object at 0xc14472c>]

I really do not understand where is the data ??? In the Rectangle ? In the Axes ?

On the Sage's side, the discussion is here :

http://ask.sagemath.org/question/359/get_minmax_data-on-implicit_plot

[1] www.sagemath.org