[Numpy-discussion] NumPy/SciPy LAPACK version

[Matthieu Brucher]

Hi,

Did you try numpy.dot(sqrtm(a), sqrtm(a)) ?

Matthieu

2007/7/16, Kevin Jacobs <jacobs@bioinformed.com> <bioinformed@gmail.com>:
>
> Hi all,
>
> This is a bit of a SciPy question, but I thought I'd ask here since I'm
> already subscribed.  I'd like to add some new LAPACK bindings to SciPy and
> was wondering if there was a minimum version requirement for LAPACK, since
> it would be ideal if I could use some of the newer 3.0 features.  In
> addition to using some block methods only added in 3.0, it is very
> convenient to use the WORK=-1 for space queries instead of reimplementing
> the underlying logic in the calc_work module.
>
> The routines of most interest to me are:
> DGELSD
> DGGGLM
> DGGLSE
>
> I've also found that SciPy's sqrtm is broken:
>
> >>> a=matrix([[59, 64, 69],
>         [64, 72, 80],
>         [69, 80, 91]])
> >>> sqrtm(a)
> array([[ 5.0084801  +1.03420519e-08j,  4.40747825 -2.06841037e-08j,
>          3.8064764  +1.03420519e-08j],
>        [ 4.40747825 -2.06841037e-08j,  4.88353492 +4.13682075e-08j,
>          5.3595916  -2.06841037e-08j],
>        [ 3.8064764  +1.03420519e-08j,  5.3595916  -2.06841037e-08j,
>          6.9127068  +1.03420519e-08j]])
> >>> sqrtm(a)*sqrtm(a)
> array([[ 25.08487289 +1.03595922e-07j,  19.42586452 -1.82329475e-07j,
>          14.48926259 +7.87335527e-08j],
>        [ 19.42586452 -1.82329475e-07j,  23.84891336 +4.04046172e-07j,
>          28.72522212 -2.21716697e-07j],
>        [ 14.48926259 +7.87335527e-08j,  28.72522212 -2.21716697e-07j,
>          47.78551529 +1.42983144e-07j]])
>
> So not even close...  (and yes, it does deserve a bug report if one
> doesn't already exist)
>
> -Kevin
>
>
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