Re: [sage-support] find_root for systems

2015-05-08 Thread Vincent Delecroix
Newton method is not useful to find all roots, it is useful to find one solution and refine approximate solutions. Built-in Sage solution: no that I know of. Doable: certainly for a large class of functions that do have a controlled behavior at infinity. You just need to localize the roots and

Re: [sage-support] find_root for systems

2015-05-08 Thread Paul Royik
I know the Newton method. My question: is there built-in support in sage and how in general find all roots? You've got approximate solution, but there is another one. On Thursday, May 7, 2015 at 12:59:22 PM UTC+3, vdelecroix wrote: On 06/05/15 14:55, Paul Royik wrote: For example,

Re: [sage-support] find_root for systems

2015-05-07 Thread Dima Pasechnik
On Wednesday, 6 May 2015 07:27:36 UTC+1, Paul Royik wrote: How can this be applied to systems? nobody really knows how to solve systems of (non-polynomial) equations in general. There are heuristics implemented in various systems... On Wednesday, May 6, 2015 at 1:28:55 AM UTC+3, Dima

Re: [sage-support] find_root for systems

2015-05-07 Thread Vincent Delecroix
On 06/05/15 14:55, Paul Royik wrote: For example, x^5+y^5=7 x*sin(y)=1 Newton method is perfectly fine here var('x,y') f(x,y) = x^5 + y^5 - 7 g(x,y) = x*sin(y) - 1 F(x,y) = (f, g) m = F.derivative() V = VectorSpace(RDF, 2) v = V((2,2)) for _ in range(10): fv = F(*v) v =

Re: [sage-support] find_root for systems

2015-05-07 Thread Jori Mäntysalo
On Thu, 7 May 2015, Dima Pasechnik wrote: nobody really knows how to solve systems of (non-polynomial) equations in general. There are heuristics implemented in various systems... What of those are built-in in Sage? -- Jori Mäntysalo

Re: [sage-support] find_root for systems

2015-05-06 Thread Paul Royik
How can this be applied to systems? On Wednesday, May 6, 2015 at 1:28:55 AM UTC+3, Dima Pasechnik wrote: On Tuesday, 5 May 2015 20:25:46 UTC+1, Paul Royik wrote: I meant without discontinuous functions. What is the general approach even in numerical solving of school functions on the

Re: [sage-support] find_root for systems

2015-05-06 Thread Jori Mäntysalo
On Tue, 5 May 2015, Paul Royik wrote: How can this be applied to systems? What kind of systems? Let us define f(x,y): f(\sqrt{2}, \sqrt[3}) = 0 f(x,y) = x^2+y^2+1 if (x is not \sqrt{2}) or (y is not \sqrt[3}) Now this clearly has a root, but no numerical method can find it. So we must have

Re: [sage-support] find_root for systems

2015-05-06 Thread Paul Royik
For example, x^5+y^5=7 x*sin(y)=1 On Wednesday, May 6, 2015 at 10:08:54 AM UTC+3, jori.ma...@uta.fi wrote: On Tue, 5 May 2015, Paul Royik wrote: How can this be applied to systems? What kind of systems? Let us define f(x,y): f(\sqrt{2}, \sqrt[3}) = 0 f(x,y) = x^2+y^2+1 if (x is not

[sage-support] find_root for systems

2015-05-05 Thread Paul Royik
How can I find numerical root for the system of equations? -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to

Re: [sage-support] find_root for systems

2015-05-05 Thread Dima Pasechnik
On Tuesday, 5 May 2015 20:25:46 UTC+1, Paul Royik wrote: I meant without discontinuous functions. What is the general approach even in numerical solving of school functions on the interval? on the interval it is the bisection method and its versions

Re: [sage-support] find_root for systems

2015-05-05 Thread Paul Royik
I meant without discontinuous functions. What is the general approach even in numerical solving of school functions on the interval? Can sage do that? On Tuesday, May 5, 2015 at 9:53:22 PM UTC+3, Dima Pasechnik wrote: This is an overtly optimistic point of view that find_root can solve any

Re: [sage-support] find_root for systems

2015-05-05 Thread Paul Royik
Thank you. I have arbitrary system of equations. I know, that find_root can solve any equation on interval. Is there something similar to system of equations? Your link didn't give answer. On Tuesday, May 5, 2015 at 7:52:11 PM UTC+3, Alexander Lindsay wrote: There's a good introduction on