[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2021-04-10 Thread Michael Jung
Unfortunately, I am not familiar with the details either. Nevertheless, I have made the proposed change for the interval -1https://mathworld.wolfram.com/AssociatedLegendrePolynomial.html. Most importantly, this also solves the problem with spherical harmonics, which was the a highly requested fi

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-04-08 Thread Eric Gourgoulhon
Hi, Le mardi 27 mars 2018 14:46:52 UTC+2, Ralf Stephan a écrit : > > > I think it will suffice for now to put the fact in the documentation. > I am afraid this is not sufficient: a consequence of this bug is that Sage gives a silly answer for something as elementary as the spherical harmonic Y_

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-27 Thread Ralf Stephan
On Tuesday, March 27, 2018 at 11:20:02 AM UTC+2, James Womack wrote: > > I have created a ticket on Sage trac for this issue: > https://trac.sagemath.org/ticket/25034 > Thanks. > As I mention in the ticket, I think that this issue raises a question as > to whether the Func_assoc_legendre_P cl

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-27 Thread James Womack
I have created a ticket on Sage trac for this issue: https://trac.sagemath.org/ticket/25034 As I mention in the ticket, I think that this issue raises a question as to whether the Func_assoc_legendre_P class is correctly defined, given that it now seems to cover both the Ferrers and associated

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-22 Thread Howard Cohl
Oh, by the way, Wolfram Mathworld is just completely wrong on this page you referenced. There is a huge difference between the two functions. Also, there is no such thing as an associated Legendre polynomial. There is a Legendre polynomials, but if you take the degrees and orders to be integers f

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-22 Thread Howard Cohl
The Ferrers functions are defined on the real segment (-1,1). The associated Legendre functions are in general defined on the Complex plane except for the ray (-\infty,1]. Typically Ferrers functions are written with argument x=\cos\theta, |x|<1 and associated Legendre functions are written with

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-22 Thread James Womack
Thanks. If that is the case, then presumably this *is* a bug in Sage Math and Func_assoc_legendre_P should distinguish the special cases for n == m when x > 1 or x < 1 when evaluating associated Legendre polynomials. Would you be able to clarify the distinction between Ferrers functions of the

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-22 Thread Howard Cohl
On Thursday, March 22, 2018 at 3:25:06 AM UTC-7, Samuel Lelievre wrote: > > Ralf wrote: > > Thanks, > > P.S. Still someone should contact DLMF with the right arguments. > > I just emailed them with cc to sage-devel. > There's nothing wrong with the formula. The Legendre function in the DLMF is

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-22 Thread James Womack
Thanks. I am waiting for an account on Sage trac, then I will submit a bug report. On Thursday, 22 March 2018 10:25:06 UTC, Samuel Lelievre wrote: > > Ralf wrote: > > Thanks, > > P.S. Still someone should contact DLMF with the right arguments. > > I just emailed them with cc to sage-devel. > --

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-22 Thread Samuel Lelievre
Ralf wrote: > Thanks, > P.S. Still someone should contact DLMF with the right arguments. I just emailed them with cc to sage-devel. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it,

[sage-devel] Re: Possible bug in gen_legendre_P (associated Legendre polynomials)

2018-03-22 Thread Ralf Stephan
arb agrees here: sage: CBF(1/2).legendre_P(1,1) [-0.8660254037844386 +/- 5.90e-17] So I'd suggest using complex balls for your numerics until the bug is fixed. Thanks, P.S. Still someone should contact DLMF with the right arguments. -- You received this message because you are subscribed to th