 # Placing a marker at specific places where lines join?

Hello,
I have a similar problem to:

Suppose I plot a line from (0,0) to (1,1.5) to (2,2). Now I want to mark
(1,1.5) with a green circle. How is that done?

I am performing a curve fit and also showing a distribution in my plot.
In order to help the reader to evaluate the result I would like to draw certain
boundaries (vertical and horizontal line).
While I am aware on how to draw such lines, I would like to know wheather there
are some functions in matplotlib which help me to retrieve the coordinates

a) at which two curves intersect
b) at which a distribution reaches a certain value?

Example:
How do I get the y-axis value which is reached by the green curve in
http://matplotlib.sourceforge.net/_images/histogram_demo_extended_021.png
a x-axis value of in 175?

I could proably use a solver from numpy like
http://docs.scipy.org/doc/numpy/reference/generated/numpy.linalg.solve.html#numpy.linalg.solve
but if I plot a distribution, the equation of the envelove is unknown at the
first place.

I'd appreciate your help or pointers to examples.

Timmie

Tim Michelsen wrote:

Hello,
I have a similar problem to:

Suppose I plot a line from (0,0) to (1,1.5) to (2,2). Now I want to mark (1,1.5) with a green circle. How is that done?

Your problem is not similar to the above; the problem above is solved with a simple call to "plot".

I am performing a curve fit and also showing a distribution in my plot.
In order to help the reader to evaluate the result I would like to draw certain
boundaries (vertical and horizontal line).
While I am aware on how to draw such lines, I would like to know wheather there
are some functions in matplotlib which help me to retrieve the coordinates

a) at which two curves intersect
b) at which a distribution reaches a certain value?

I think this is strictly a computational problem, not a plotting problem, so I suggest you post the question to the numpy or scipy lists.

Eric

···

Example:
How do I get the y-axis value which is reached by the green curve in http://matplotlib.sourceforge.net/_images/histogram_demo_extended_021.png
a x-axis value of in 175?

I could proably use a solver from numpy like
http://docs.scipy.org/doc/numpy/reference/generated/numpy.linalg.solve.html#numpy.linalg.solve
but if I plot a distribution, the equation of the envelove is unknown at the
first place.

I'd appreciate your help or pointers to examples.