basically I want to graph two functions
g1 = x*cos(x*pi)
g2 = 1 - 0.6x^2
and then plot the intersection, I already have a module that takes inputs close to the two lines intersections, and then converges to those points (there's four of them)
but I want to graph these two functions and their intersections using matplotlib but have no clue how. I've only graphed basic functions. Any help is greatly appreciated
Assuming you can get as far as plotting one function, with x and g1 as numpy arrays,
pylab.plot(x,g1)
just call plot again (and again) to draw any number of separate curves:
pylab.plot(x,g2)
finally display or save to a file:
pylab.show()
To indicate a special point such as an intersection, just pass in scalars for x, y and ask for a marker such 'x' or 'o' or whatever else you like.
pylab.plot(x_intersect, y_intersect, 'x', color="#80C0FF")
Alternatively, I often mark a special place along x with a vertical segment by plotting a quick little two-point data set:
pylab.plot( [x_special, x_special], [0.5, 1.9], '-b' )
I may hardcode the y values to look good on a plot for my current project, but obviously this is not reusable for other projects. Note that plot() can take ordinary python lists; no need to convert to numpy arrays.
If you can't get as far as plotting one function (just g1) then you need a basic tutorial in matplot lib, which wouldn't make a good answer here but please go visit http://matplotlib.org/ and google "matplotlib tutorial" or "matplotlib introduction".
ax.axhline and ax.axvline.