Yeah, a lot of work is needed in sets.
I see that error on master but not on my PR:
https://github.com/sympy/sympy/pull/17593
There it doesn't raise but just returns unevaluated:
In [3]: simplify(a.intersect(b))
Out[3]: {(t, t) | t ∊ [0, 1]} ∩ {(1 - t, t) | t ∊ [0, 1]}
There is no code to handle intersections of this kind of ImageSet yet.
Oscar
On Tue, 1 Oct 2019 at 23:30, EKW <etk...@gmail.com> wrote:
>
> OK, I wasn't sure if that was the intended way, since using tuples quickly
> leads to errors such as:
>
> >>> a = ImageSet(Lambda(t, (t, t)), Interval(0, 1))
> >>> a
> ImageSet(Lambda(t, (t, t)), Interval(0, 1))
> >>> (0,0) in a
> True
> >>> b = ImageSet(Lambda(t, (1 - t, t)), Interval(0, 1))
> >>> b
> ImageSet(Lambda(t, (1 - t, t)), Interval(0, 1))
> >>> a.intersect(b)
> Intersection(ImageSet(Lambda(t, (t, t)), Interval(0, 1)), ImageSet(Lambda(t,
> (1 - t, t)), Interval(0, 1)))
> >>> simplify(a.intersect(b))
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/home/eward/se/sympy/simplify/simplify.py", line 582, in simplify
> return done(expr)
> File "/home/eward/se/sympy/simplify/simplify.py", line 541, in done
> rv = e.doit() if doit else e
> File "/home/eward/se/sympy/core/basic.py", line 1691, in doit
> for term in self.args]
> File "/home/eward/se/sympy/core/basic.py", line 1691, in <listcomp>
> for term in self.args]
> File "/home/eward/se/sympy/sets/fancysets.py", line 460, in doit
> return SetExpr(base_set)._eval_func(f).set
> File "/home/eward/se/sympy/sets/setexpr.py", line 84, in _eval_func
> res = set_function(func, self.set)
> File "/home/eward/se/sympy/sets/sets.py", line 2255, in set_function
> return _set_function(f, x)
> File "/home/eward/se/sympy/multipledispatch/dispatcher.py", line 198, in
> __call__
> return func(*args, **kwargs)
> File "/home/eward/se/sympy/sets/handlers/functions.py", line 70, in
> _set_function
> sing = [i for i in singularities(expr, var)
> File "/home/eward/se/sympy/calculus/singularities.py", line 83, in
> singularities
> if not expression.is_rational_function(symbol):
> AttributeError: 'Tuple' object has no attribute 'is_rational_function'
>
> On Tuesday, October 1, 2019 at 2:58:20 PM UTC-7, EKW wrote:
>>
>> For example if I wanted to represent the line segment from (0,0) to (1,1)
>> (f(t) = (t, t) for t in (0, 1))- can this be done with an image set? How? Or
>> a curve in 3d space (for example, f(t) = (t^2, t, 1 - t) for t in (0, 1)).
>
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