Christopher Smith

factor should return unhandled expressions unchanged

8

``` >>> factor(Piecewise((x*(x+2),x

bool_equal doesn't handle expressions with Dummy well

1

Dummy symbols created with no name default to having a name that is a number. Dummies don't round-trip through S(Dummy('x').name), however, for two reasons: a Symbol rather than a Dummy...

cancel should work with primitive of expression

5

``` An expression `z` was obtained as follows: # eq = q*x + q/4 + x**4 + x**3 + 2*x**2 - S(1)/3 # z = eq.subs(x, solve(eq, x)[0]) z =...

add combinatorics cheatsheet

9

I've spent a lot of time working on the combinatorics functions and a cheatsheet of the different options would be good to add. Here are my notes thus far (as...

cheatsheet for factor, et all

1

I'm just posting a link to the page where my work in progress on a document to contrast the different expression (re)factoring tools. https://gist.github.com/4140846 Original issue for #6629: http://code.google.com/p/sympy/issues/detail?id=3530 Original...

canonical way to know if you are dealing with SymPy object

2

I was surprised to (re)learn that Matrix does not derive from Basic. What is the most canonical way to know you are dealing with a SymPy object? ```python >>> isinstance(eye(2),...

let decompose_power handle base reduction

14

#### References to other Issues or PRs #5149 #### Brief description of what is fixed or changed By decomposing a Rational base into a perfect power, cases where two generators...

Set recursion error

3

The following raises a recursion error: ``` >>> U = S.Complexes >>> U -= U.intersect(Ne(x, 1).as_set()) >>> U -= U.intersect(S.true.as_set()) ... RecursionError: maximum recursion depth exceeded ```

Plane.distance(Line) wrong

6

```python >>> plane = Plane((0,0,0),(1,0,0),(1,1,0)) >>> plane.distance(Line((x,y,z),(1,1,1))) 0 >>> plane.distance(Line((x,x,y),(1,1,1))) 0 >>>plane.distance(Line((0,0,1),(1,1,1))) 1 ``` The symbolic case should not return 0 as we can see there is a non-zero case.

There is perhaps some cleaning up of how the `contains` and `_contains` routines do their respective jobs per discussion in #25133. It is not clear when where unevaluated Contains and...