I'm sorry, I don't follow what you are saying.

Aaron Meurer

On Fri, Mar 16, 2012 at 10:24 PM, Abhishek Aggarwal
<[email protected]> wrote:
> Hi,
>  If we can treat C1 also as a variable 'y' then it won't lost its
> properties, as variable do not couple up and simplify to form a new
> variable. So may be this can work.
>
> regards--
> Abhishek Aggarwal
> Computer Science 2nd year IIT DELHI
>
>
> On Thursday, 15 March 2012 09:44:33 UTC+5:30, Aaron Meurer wrote:
>>
>> Hi.
>>
>> I just created http://code.google.com/p/sympy/issues/detail?id=3148.
>> The issue is related to constantsimp() in the ODE module.  Basically,
>> right now, it converts things like 2*C1 + C1**2*x + (C1 + 1)*x**2 into
>> C1 + C2*x + C3*x**2.  In other words, it absorbs C1, C2, ... constants
>> into other constants and into each other, and then renumbers them,
>> because they are no longer the same constant.
>>
>> I think this is a bad idea, because it makes it look like C1, C2, and
>> C3 are independent of each other, when they really aren't (because, in
>> this example, C2 = C1**2/4 and C3 = C1/4 + 1).  What I think it should
>> do instead is return something like C1 + C1**2/2**2 + (C1/4 + 1)*x**2.
>>  In other words, simplify one constant, and rewrite the others in
>> terms of it.
>>
>> The question is, how do you determine how to do this?  Has anyone ever
>> considered such an algorithm?  The idea is that you have an
>> over-determined system of several equations, and you want to rewrite
>> the equations in terms of some new unknowns so that the whole system
>> becomes simpler. I think that idea could also be useful in solve(),
>> except there you also need to care about the relationship between the
>> new system variables and the old ones, and how simple they are.
>>
>> Does anyone have any thoughts on how this could be achieved?
>>
>> Aaron Meurer
>
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