On Wed, Oct 30, 2013 at 9:00 PM, Alexander Birukov <[email protected]> wrote:
> Task is: find image/preimage, if you have n f-s, its interval(-s) (if empty,
> then (-oo, +oo)) and user interval input.
> Example:
> 2
> x**4 - 16x - function
> [14, 55) - func interval
> 2*x - 4
> [0, 44]
>
> 1
> [54, +oo) - user interval
>
> I'm parsing input with regexp transforming input to sympy-understandable
> data, then I have to Intersect interval user gave and intervals of function
> and so on.
Just use sympify()
Aaron Meurer
>
> Here comes another problem. It was done w/o sympy few days ago, but once you
> hit functions like x**3 - 3*x, you're gonnna find y' (and question right now
> how I'm supposed to find the higher exponent in eq, but I think it's
> possible), and then solve it. Finding y' isnt that hard, it's another
> parsing work, but it req. lots of presets: replace this to that etc. Then I
> look a bit future and I see: more problems comes, so I decided to use SymPy.
>
> So I've done input, I have something like that right now:
>
> 1
> x*3 - 55
>
> 1
> [3, 56)
>
>
> {0: [3*x - 55, (-oo, oo)]} - data stores in dict keyed by non-negative
> integers, it already finds intersection and replacing it to new interval.
>
> четверг, 31 октября 2013 г., 2:27:08 UTC+4 пользователь Christophe Bal
> написал:
>>
>> Hello,
>> I think that this problem is impossible to solve in general.
>>
>> What are the functions you want to study ?
>>
>> Christophe, a simple user
>>
>>
>> 2013/10/30 Alexander Birukov <[email protected]>
>>>
>>> Hello everyone.
>>>
>>> Was wondering how can I get an image of function if I have an interval
>>> for it (problem comes if I have unioned intervals. I dont know how can I
>>> call each interval start/end or at least split union into Nth intervals).
>>> SymPy docs gives info about transform. but I've browsed source code and it's
>>> not even loaded as well as out of source files. So, it's taken away?
>>>
>>> Example of what I want (basically, it can be any function, keyboard
>>> input):
>>>
>>> f : R -> R
>>> f(x) = x**3 - 3*x, x in R
>>>
>>> f([0, sqrt(3)] = [-2, 0]
>>>
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>>
>>
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