Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-21 Thread maldun
Well I guess doing symbolic computation in a clean fashion is never easy ... I'm not unfimiliar with the notion of Picard-Vessiot extensions, but I will have a second look into it. Thanks for the input. On Friday, December 20, 2013 8:19:33 PM UTC+1, Nils Bruin wrote: > > On Friday, December 20

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-20 Thread Nils Bruin
On Friday, December 20, 2013 2:58:51 AM UTC-10, maldun wrote: > > Another more careful approach would be to start at the field of rational > functions and extend it step by step with algebraic and transcendental > functions, till we reach a field which is maximal under the available > symbolic e

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-20 Thread maldun
Another more careful approach would be to start at the field of rational functions and extend it step by step with algebraic and transcendental functions, till we reach a field which is maximal under the available symbolic expressions. On Friday, December 20, 2013 9:26:22 AM UTC+1, maldun wrote

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-20 Thread maldun
On Thursday, December 19, 2013 7:47:19 PM UTC+1, Nils Bruin wrote: > On Wednesday, December 18, 2013 11:04:22 PM UTC-10, maldun wrote: >> >> What I mean is that we should only allow expressions of meromorphic >> functions in the symbolic field, i.e. we would only allow variables, >> trigonometri

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread Vincent Delecroix
And meromorphic functions are not stable under composition... 2013/12/19, Nils Bruin : > On Wednesday, December 18, 2013 11:04:22 PM UTC-10, maldun wrote: >> >> What I mean is that we should only allow expressions of meromorphic >> functions in the symbolic field, i.e. we would only allow variable

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread Nils Bruin
On Wednesday, December 18, 2013 11:04:22 PM UTC-10, maldun wrote: > > What I mean is that we should only allow expressions of meromorphic > functions in the symbolic field, i.e. we would only allow variables, > trigonometric functions and so on. > SR should be then a superset where everything els

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread maldun
Sorry my Mistake, but if you look into the text you quoted, I already corrected it: ... > ... The ring of analytic > functions is an Integral domain. ... Continous is of course not sufficient. On Thursday, December 19, 2013 10:12:15 AM UTC+1, John Cremona wrote: > > On 19 December 2013 09:04,

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread maldun
Sorry my Mistake, but if you look into the text you quoted, I already it: ... > that the Kronecker delta is not a continuous function. The ring of analytic > functions is an Integral domain. ... Continous is of course not sufficient. On Thursday, December 19, 2013 10:12:15 AM UTC+1, John Crem

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread John Cremona
On 19 December 2013 09:04, maldun wrote: > The fact, that SR is not a field is interesting, the Kronecker delta example > on the ticket shows it quite well. But the problem originates from the fact, > that the Kronecker delta is not a continuous function. The ring of analytic > functions is an Int

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread maldun
The fact, that SR is not a field is interesting, the Kronecker delta example on the ticket shows it quite well. But the problem originates from the fact, that the Kronecker delta is not a continuous function. The ring of analytic functions is an Integral domain. Question: Should we define a subs

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread maldun
This isn't exactly a question of mathematical correctness, but of usability. Think of users who aren't mathematicians, but engineers or from physics. Most of them even don't know the difference between a polynomial from ZZ or RR. So the goal should be a good default behavior which covers 70-90% o

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread maldun
This isn't exactly a question of mathematical correctness, but of usability. Think of users who aren't mathematicians, but engineers or from physics. Most of them even don't know the difference between a polynomial from ZZ or RR. So the goal should be a good default behavior which covers 70-90% o

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread maldun
The fact, that SR is not a field is interesting, the Kronecker delta example on the ticket shows it quite well. But the problem originates from the fact, that the Kronecker delta is not a continuous function. The ring of continuous functions is an Integral domain. Question: Should we define a su

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-19 Thread maldun
The fact, that SR is not a field is interesting, the Kronecker delta example on the ticket shows it quite well. But the problem originates from the fact, that the Kronecker delta is not a continuous function. The ring of continuous functions is an Integral domain. Question: Should we define a su

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-18 Thread Nils Bruin
On Wednesday, December 18, 2013 9:58:15 AM UTC-8, vdelecroix wrote: > > Users of polynomials should worry about the coefficient ring. What do > someone should expect of > > sage: (6*x^2 - 12).factor() > > The answers are different in ZZ[x], QQ[x] and RR[x]. For a symbolic > polynomial there

Re: [sage-devel] Re: SymbolicPolynomial class

2013-12-18 Thread Vincent Delecroix
Users of polynomials should worry about the coefficient ring. What do someone should expect of sage: (6*x^2 - 12).factor() The answers are different in ZZ[x], QQ[x] and RR[x]. For a symbolic polynomial there is no way to make it coherent... Moreover, I feel very uncomfortable having an extra

[sage-devel] Re: SymbolicPolynomial class

2013-12-18 Thread maldun
Why reinvent the wheel? A symbolic polynomal class should be capable of a type checking of the coefficients and transform the polynomial internally into the correct setting and then call the correct algorithms and methods. The main purpose of such a class is that the user can work intuitively wi

[sage-devel] Re: SymbolicPolynomial class

2013-12-18 Thread Simon King
Hi again, On 2013-12-18, maldun wrote: > 1) I think that applying Polynomial division by commands like > > sage: f(x)=3Dx^3+5*x^2-3*x+1 > sage: g(x)=3Dx+1 > sage: f.maxima_methods().divide(g) > [x^2 + 4*x - 7, 8] > > are not very intuitive. These aren't polynomials but symbolic expressions. If y

[sage-devel] Re: SymbolicPolynomial class

2013-12-18 Thread Simon King
Hi, On 2013-12-18, maldun wrote: > --=_Part_1054_13775092.1387359867313 > Content-Type: text/plain; charset=ISO-8859-1 > > And another thing: A more unified interface for polynomials. > > Currently we have, as you mentioned, three ways to define polynomials. No, we have only one. The other t

[sage-devel] Re: SymbolicPolynomial class

2013-12-18 Thread maldun
And another thing: A more unified interface for polynomials. Currently we have, as you mentioned, three ways to define polynomials. It would enable us to design a class which provides a good default behavior for the average user. -- You received this message because you are subscribed to the G

[sage-devel] Re: SymbolicPolynomial class

2013-12-18 Thread maldun
1) I think that applying Polynomial division by commands like sage: f(x)=x^3+5*x^2-3*x+1 sage: g(x)=x+1 sage: f.maxima_methods().divide(g) [x^2 + 4*x - 7, 8] are not very intuitive. This should be done by specific methods/operators for polynomials, and this can only be done by a specific class f

[sage-devel] Re: SymbolicPolynomial class

2013-12-17 Thread Simon King
Hi, On 2013-12-17, maldun wrote: > On ticket http://trac.sagemath.org/ticket/9706 for the orthogonal > Polynomials Jeroen Demeyer came up with the the idea of a > SymbolicPolynomial class. I think that's a great idea, because, if well > designed, such a class has much potential to give very mu