From jrheinlaender at gmx.de  Sat Nov  2 12:11:06 2024
From: jrheinlaender at gmx.de (=?UTF-8?Q?Jan_Rheinl=C3=A4nder?=)
Date: Sat, 2 Nov 2024 12:11:06 +0100
Subject: [GiNaC-devel] Find length of a vector
Message-ID: <3529e995-0b49-4dcd-9737-ee4aed545cd2@gmx.de>

Hi,

trying to find the length of a vector by taking the square root of the 
scalar product, I get this (in ginsh):

> v = [[a,b]];
[[a,b]]
 > r = sqrt(v * transpose(v));
sqrt([[a,b]]*[[a],[b]])
 > evalm(r);
matrix::pow(): don't know how to handle exponent

The reason is that the scalar product evaluates to a matrix with a 
single element, not to a numeric. Is that intended?

Thanks,

Jan Rheinl?nder

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From kreckel at in.terlu.de  Sat Nov  2 12:31:21 2024
From: kreckel at in.terlu.de (Richard B. Kreckel)
Date: Sat, 2 Nov 2024 12:31:21 +0100
Subject: [GiNaC-devel] Find length of a vector
In-Reply-To: <3529e995-0b49-4dcd-9737-ee4aed545cd2@gmx.de>
References: <3529e995-0b49-4dcd-9737-ee4aed545cd2@gmx.de>
Message-ID: <08bd21ec-56a1-47e8-b0e4-b816b32903be@in.terlu.de>

Hi,

On 11/2/24 12:11 PM, Jan Rheinl?nder via GiNaC-devel wrote:
> trying to find the length of a vector by taking the square root of the 
> scalar product, I get this (in ginsh):
> 
>> v = [[a,b]];
> [[a,b]]
>  > r = sqrt(v * transpose(v));
> sqrt([[a,b]]*[[a],[b]])
>  > evalm(r);
> matrix::pow(): don't know how to handle exponent
> 
> The reason is that the scalar product evaluates to a matrix with a 
> single element, not to a numeric.

There are just matrix products evaluating to matrices. There is no 
special case for scalar products (apart from the quite special stuff in 
indexed.h).

> Is that intended?

Well, it's the way it is designed.  ;-)

   -richy.
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From git at ginac.de  Tue Nov 26 00:33:47 2024
From: git at ginac.de (git service)
Date: Tue, 26 Nov 2024 00:33:47 +0100 (CET)
Subject: [GiNaC-devel] [SCM] GiNaC -- a C++ library for symbolic
 computations branch master updated. release_1-4-0-779-g32702f84
Message-ID: <20241125233347.D0379D81824@cebix.net>

This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GiNaC -- a C++ library for symbolic computations".

The branch, master has been updated
       via  32702f847fb49da649f4362b0de3084890ac8129 (commit)
      from  0aa0a0c6fe7d24fdc41af01581e8728054393740 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
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- Log -----------------------------------------------------------------
commit 32702f847fb49da649f4362b0de3084890ac8129
Author: Richard Kreckel <kreckel at ginac.de>
Date:   Tue Nov 26 00:21:28 2024 +0100

    Avoid "expression with side effects..." warning using ex_to<T>().
    
    Clang++ warns that instantiations of this inline template function
    ex_to<T>(const ex &) are "expression with side effects [that] will be
    evaluated despite being used as an operand to 'typeid'".
    
    Let's declare this ex_to<T>() as a pure function (i.e. having no
    side effects) for compilers which support __attribute__((__pure__)).
    
    GCC seems to support this attribute since more than ten years.

-----------------------------------------------------------------------

Summary of changes:
 ginac/compiler.h | 2 ++
 ginac/ex.h       | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)


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GiNaC -- a C++ library for symbolic computations