Very nice ! I wasn’t aware of it… Now a couple questions/remarks :

   - 
   
   Is there a reason for this being implemented for ComplexBallField but 
   not for ComplexField (except CDF) ? What about ComplexIntervalField ?
   - 
   
   I am not aware of anything comparing the abilities of the various 
   numerical tools available in Sagemath in the documentation. Did I miss it ?
   
At the very least, a tutorial illustrating them would be useful. A better 
(but possibly quite heavier) text would be additions to the numerical 
computing chapters of a new edition of *Computational mathematics with 
Sagemath*, which is more and more in order…

What do you think ?
​
Le vendredi 11 juin 2021 à 21:27:05 UTC+2, vdelecroix a écrit :

> Le 11/06/2021 à 20:22, Dima Pasechnik a écrit :
> > On Fri, 11 Jun 2021, 18:25 Emmanuel Charpentier, <
> > emanuel.c...@gmail.com> wrote:
> > 
> >> OK. That was not an error of mine (nor my Sage installation), but a a
> >> genuine problem. So no indication to file a ticket.
> >>
> >> Note : Numerics with"standard" are not a problem :
> >>
> >> sage: %time matrix([[CDF(u) for u in v] for v in 
> pM]).eigenvectors_right()
> >> CPU times: user 1.95 ms, sys: 15 µs, total: 1.96 ms
> >> Wall time: 1.85 ms
> >> [(-1.5855741097050124 - 1.9835895314317984*I,
> >> [(0.9524479486112228, -0.2837102376875301 - 0.11002559239003057*I,
> >> 0.011400252227268036 - 0.010761481586469179*I)],
> >> 1),
> >> (0.10840730449357763 + 1.6730496133213792*I,
> >> [(0.8835538411020463, 0.2631022513327894 - 0.3627905504445216*I,
> >> 0.05890961187635257 + 0.12256626515553348*I)],
> >> 1),
> >> (0.4060235736555931 + 2.708455679766778*I,
> >> [(0.8864942697472706, 0.26813150779882816 - 0.24992379361655742*I,
> >> -0.24416421274380526 - 0.14196949964794017*I)],
> >> 1)]
> >>
> >> But if you need extended precision, there's a snag :
> >>
> >> ```
> >> sage: C= ComplexField(200)
> >> sage: %time foo = matrix([[C(u) for u in v] for v in
> >> pM]).eigenvectors_right()
> >> <timed exec>:1: UserWarning: Using generic algorithm for an inexact 
> ring,
> >> which may result in garbage from numerical precision issues.
> >>
> > 
> > in fact, arb has some linear algebra implemented, only that functionality
> > is not wrapped in Sage.
>
> hmmm, 10 years ago it was indeed not in sage but
>
> sage: sM = matrix(3, [-sqrt(2) - 1, 1/4*I*sqrt(759) - 1/4, -2*sqrt(3),
> ....: 1/2*I*sqrt(3) + 1/2, 1/8*sqrt(33) + 1/8, -1/5*sqrt(29) + 3/5,
> ....: 0, 1/4, 1/2*I*sqrt(23) + 1/2])
> sage: sM.change_ring(ComplexBallField(256)).eigenvectors_right_approx()
> <ipython-input-2-597c50ed1766>:1: FutureWarning: This 
> class/method/function is marked as experimental. It, its functionality 
> or its interface might change without a formal deprecation.
> See https://trac.sagemath.org/30393 for details.
> sM.change_ring(ComplexBallField(Integer(256))).eigenvectors_right_approx()
> [([-1.585574109705012818320754555380077143033164486087030751802791286603000260637687
>  
>
> +/- 3.06e-79] - 
> [1.983589531431798407272840921819657822844388213332549281429493414447825431290207
>  
>
> +/- 3.05e-79]*I,
>
> [([-0.7645889954375910796175588680760753644497544472611288268496784517551156034840851
>  
>
> +/- 3.49e-80] + 
> [0.5679443307838031693126382504352883182783867453515207101490113908352846374511589
>  
>
> +/- 4.71e-80]*I, 
> [0.2933600072059874975695356608056928703375239897336479003693686118090527352449637
>  
>
> +/- 2.62e-80] - 
> [0.08085193950422595460559726747128398322364244288273211664977438986727139956036997
>  
>
> +/- 1.86e-81]*I, 
> [-0.002734621817507568627793755191059520745414855464984622057215624183928681966128039
>  
>
> +/- 3.48e-83] + 
> [0.01543687404549433149004830726668865175938723340836903249472149019570000983681407
>  
>
> +/- 6.01e-82]*I)],
> 1),
>
> ([0.1084073044935780329693711992135459902927450863702466775904749191406132984593997
>  
>
> +/- 2.35e-80] + 
> [1.673049613321379085900796686139959744878064234423412272818114017801709044221350
>  
>
> +/- 4.95e-79]*I,
>
> [([-0.2673371902772041016297440268511643741966917470300012123253823050737523650735768
>  
>
> +/- 3.44e-80] - 
> [0.02255276973433239605480951065284270406141140134762632616605864073042511737197782
>  
>
> +/- 6.64e-82]*I, 
> [-0.08886719147182478198522558738553193426651781904829084677832088009136722752956601
>  
>
> +/- 2.61e-81] + 
> [0.1030539596890842335569665014655476103537849006257746372204680855562700952313454
>  
>
> +/- 1.45e-80]*I, 
> [-0.01469578961696251938128853753478067963226607548513094281484268115068461631364436
>  
>
> +/- 3.99e-82] - 
> [0.03858858880485532751435734250502627274540851776921042689105965744221705829132246
>  
>
> +/- 3.42e-81]*I)],
> 1),
>
> ([0.4060235736555933190310210654841992389482805815876850469981213132923920738981516
>  
>
> +/- 2.51e-80] + 
> [2.708455679766779092170763267761045037964677499861201681854033953870245005022438
>  
>
> +/- 1.50e-79]*I,
>
> [([0.2103718533466063742076462260260793168410401002165862474556218965077763660977134
>  
>
> +/- 3.27e-80] + 
> [0.05448236953479104093710977337474251123511802942923003190706717417804356762302697
>  
>
> +/- 3.17e-81]*I, 
> [0.07898952661654168047766696024137805415491440866540645841786257582178406891492673
>  
>
> +/- 1.47e-81] - 
> [0.04282993479195057509885682538044990967004220531263985306993932362186424999425426
>  
>
> +/- 2.1e-84]*I, 
> [-0.04921683614015854406786925932481355184588924524472501364264944877387240329246417
>  
>
> +/- 4.04e-82] - 
> [0.04869634593105051448079497440445424999631243725298577782757982000687160120825688
>  
>
> +/- 3.53e-81]*I)],
> 1)]
>

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