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Ublas : |
Subject: Re: [ublas] [bindings] lapack::lange: where is the computed norm?
From: Karl Meerbergen (Karl.Meerbergen_at_[hidden])
Date: 2010-07-23 03:25:53
Hi,
There seems indeed something to be wrong with the bindings here. lange()
should return a float where it does not do this currently. In lapack.h
the lange functions return void, which does not seem to be correct.
Best,
Karl
Marco Guazzone wrote:
> On Thu, Jul 22, 2010 at 11:15 PM, Rutger ter Borg <rutger_at_[hidden]> wrote:
>
>> Marco Guazzone wrote:
>>
>>
>>> Hi,
>>>
>>> According to LAPACK the ?LANGE function should return the computed norm.
>>>
>>> For instance, see:
>>> http://www.netlib.org/lapack/explore-html/a00725_source.html
>>>
>>> However, in lapack::lange I'm not able to find neither a return value
>>> nor an output parameter representing that norm.
>>>
>>> Can you help me?
>>>
>>> Thank you very much!!
>>>
>>> Best,
>>>
>>> -- Marco Guazzone
>>>
>> Looks like a LAPACK function that returns stuff, and doesn't have an INFO
>> parameter. I.e., it looks more like a BLAS function than like LAPACK
>> function. Perhaps there's more in auxiliary that behaves like this?
>>
>>
>
> Hi,
>
> In auxiliary, there are a family of ?LAN?? functions
> http://www.netlib.org/lapack/lug/node144.html
>
> used for computing the norm of a matrix.
> These functions differ from the type of matrix they work with.
> For instance, ?LANGE works with general matrices, while ?LANGB work
> with general banded matrices and ?LANHB works with Hermitian banded
> matrices.
> It appears that all these functions are FORTRAN FUNCTION returning some value.
> In bindings, it seems they are implemented as FORTRAN SUBROUTINE
> (i.e., returns a std::ptrdiff_t instead of the value computed by the
> function).
>
> Cheers,
>
> -- Marco
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