Re: [sympy] Re: Can SymPy's existing set implementation handle parameterized curves?
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 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 "", line 1, in
> 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
> 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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[sympy] Re: Can SymPy's existing set implementation handle parameterized curves?
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 "", line 1, in 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 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)). > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/9124ca80-5099-4f44-9441-f82af3f9de12%40googlegroups.com.
Re: [sympy] Can SymPy's existing set implementation handle parameterized curves?
Yes, you can do that with ImageSet:
In [11]: ImageSet(Lambda(t, (t, t)), Interval(0, 1))
Out[11]: {(t, t) | t ∊ [0, 1]}
In [14]: ImageSet(Lambda(t, (t**2, t, 1-t)), Interval(0, 1))
Out[14]:
⎧⎛ 2 ⎞ ⎫
⎨⎝t , t, 1 - t⎠ | t ∊ [0, 1]⎬
⎩ ⎭
On Tue, 1 Oct 2019 at 22:58, 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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[sympy] Can SymPy's existing set implementation handle parameterized curves?
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)). -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/8d96f817-802e-412e-948f-a3fc18361419%40googlegroups.com.
[sympy] Good talk on documentation
I meant to share this at the beginning of Google Season of Docs but I couldn't find it until now. This is a talk that was shared by the GSoD admins at some point. https://www.youtube.com/watch?v=t4vKPhjcMZg There's also a blog post version of the talk if you don't have time to watch it. https://www.divio.com/blog/documentation/ The talk does a good job of clarifying the different kinds of documentation how they should be separated. We do a decent but not perfect job of having this separation in our SymPy docs, and it might help to make the separation clearer, as suggested at the end of the talk. Aaron Meurer -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6JeGMnjf_qjMqp9iOHdoRZ9ir2J9ny8Ve-T%2B8z-ydSuxQ%40mail.gmail.com.
