Issue 1172: example: curve sketching
http://code.google.com/p/sympy/issues/detail?id=1172
New issue report by Vinzent.Steinberg:
It's a common task for German high school students to do a so called curve
sketching, which means basically analyzing a function f(x) using
derivatives and stuff. This is rather tedious, so it's nice to let sympy do
the work for you!
Here is an incomplete script for this. The current output:
graph discussion for f(x) = -9*x + x**3
f is symmetric to point of origin.
limes for x -> oo: oo
limes for x -> -oo: -oo
intersections with x-axis:
(3, 0)
(-3, 0)
(0, 0)
intersection with y-axis:
(0, 0)
minimum at (3**(1/2), -6*3**(1/2))
maximum at (-3**(1/2), 6*3**(1/2))
inflection point at (0, 0)
graph discussion for f(x) = 4*x*(1 - a*x**(1/2))
intersections with x-axis:
(0, 0)
intersection with y-axis:
(0, 0)
minimum at (4/(9*a**2), 16/(27*a**2))
graph discussion for f(x) = x**x
limes for x -> oo: oo
limes for x -> -oo: oo
intersections with x-axis:
none
intersection with y-axis:
(0, 1)
Traceback (most recent call last):
File "graph.py", line 78, in <module>
graph_discussion(f, limits=limits)
File "graph.py", line 55, in graph_discussion
inflections = solve(d2f, x)
File "sympy/solvers/solvers.py", line 89, in solve
result = [tsolve(f, *symbols)]
File "sympy/solvers/solvers.py", line 605, in tsolve
assert False, 'tsolve: at least one Function expected at this point'
AssertionError: tsolve: at least one Function expected at this point
As you can see, solve fails to find the minimum at x=1/e.
And for f2 (see code) the limits had to be disabled, calculating them did
not finish after several minutes.
Attachments:
graph.py 2.3 KB
Issue attributes:
Status: Started
Owner: Vinzent.Steinberg
Labels: Type-Enhancement Priority-Medium
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