From kisilv at maths.leeds.ac.uk  Thu Oct  1 17:21:18 2009
From: kisilv at maths.leeds.ac.uk (Vladimir V. Kisil)
Date: Thu, 01 Oct 2009 16:21:18 +0100
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC3D00D.9060406@ginac.de>
References: <31192.1253970592@krein.leeds.ac.uk> <4AC3D00D.9060406@ginac.de>
Message-ID: <2682.1254410478@krein.leeds.ac.uk>

		Dear Richard,

>>>>> On Wed, 30 Sep 2009 23:39:25 +0200, "Richard B. Kreckel" <kreckel at ginac.de> said:

    RK> The rewriting rule pow(exp(x),a) -> exp(a*x) is not correct in
    RK> the general complex case. Consider a=1/2 and x=-I*Pi, for
    RK> instance. 

	Thanks for pointing out this. I am attaching a patch which do the
  substitution only for real x and a.

  Best wishes,
  Vladimir
-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/
-------------- next part --------------
--- inifcns_trans.cpp	2009-02-17 13:39:22.000000000 +0000
+++ patches/inifcns_trans.cpp	2009-10-01 16:03:58.000000000 +0100
@@ -99,9 +99,18 @@
 	return exp(GiNaC::real_part(x))*sin(GiNaC::imag_part(x));
 }
 
+static ex exp_power(const ex & x, const ex & a)
+{
+	if (x.info(info_flags::real) && a.info(info_flags::real))
+		return exp(x*a);
+
+	return power(exp(x), a).hold();
+}
+
 REGISTER_FUNCTION(exp, eval_func(exp_eval).
                        evalf_func(exp_evalf).
                        derivative_func(exp_deriv).
+                       power_func(exp_power).
                        real_part_func(exp_real_part).
                        imag_part_func(exp_imag_part).
                        latex_name("\\exp"));

From stephen at missouri.edu  Thu Oct  1 17:49:03 2009
From: stephen at missouri.edu (Stephen Montgomery-Smith)
Date: Thu, 01 Oct 2009 10:49:03 -0500
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <2682.1254410478@krein.leeds.ac.uk>
References: <31192.1253970592@krein.leeds.ac.uk> <4AC3D00D.9060406@ginac.de>
	<2682.1254410478@krein.leeds.ac.uk>
Message-ID: <4AC4CF6F.3070104@missouri.edu>

Vladimir V. Kisil wrote:
> 		Dear Richard,
> 
>>>>>> On Wed, 30 Sep 2009 23:39:25 +0200, "Richard B. Kreckel" <kreckel at ginac.de> said:
> 
>     RK> The rewriting rule pow(exp(x),a) -> exp(a*x) is not correct in
>     RK> the general complex case. Consider a=1/2 and x=-I*Pi, for
>     RK> instance. 
> 
> 	Thanks for pointing out this. I am attaching a patch which do the
>   substitution only for real x and a.

It will also be true for arbitrary x if a is an integer.


From kisilv at maths.leeds.ac.uk  Thu Oct  1 22:57:14 2009
From: kisilv at maths.leeds.ac.uk (Vladimir V. Kisil)
Date: Thu, 01 Oct 2009 21:57:14 +0100
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC4CF6F.3070104@missouri.edu>
References: <31192.1253970592@krein.leeds.ac.uk> <4AC3D00D.9060406@ginac.de>
	<2682.1254410478@krein.leeds.ac.uk> <4AC4CF6F.3070104@missouri.edu>
Message-ID: <13436.1254430634@krein.leeds.ac.uk>

>>>>> On Thu, 01 Oct 2009 10:49:03 -0500, Stephen Montgomery-Smith <stephen at missouri.edu> said:
    SMS> It will also be true for arbitrary x if a is an integer.

	Good point! The third iteration of the patch is attached.

-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/
-------------- next part --------------
--- inifcns_trans.cpp	2009-02-17 13:39:22.000000000 +0000
+++ patches/inifcns_trans.cpp	2009-10-01 21:04:09.000000000 +0100
@@ -99,9 +99,19 @@
 	return exp(GiNaC::real_part(x))*sin(GiNaC::imag_part(x));
 }
 
+static ex exp_power(const ex & x, const ex & a)
+{
+	if (x.info(info_flags::integer) || a.info(info_flags::integer)
+		|| (x.info(info_flags::real) && a.info(info_flags::real)))
+		return exp(x*a);
+
+	return power(exp(x), a).hold();
+}
+
 REGISTER_FUNCTION(exp, eval_func(exp_eval).
                        evalf_func(exp_evalf).
                        derivative_func(exp_deriv).
+                       power_func(exp_power).
                        real_part_func(exp_real_part).
                        imag_part_func(exp_imag_part).
                        latex_name("\\exp"));

From kreckel at ginac.de  Fri Oct  2 00:00:13 2009
From: kreckel at ginac.de (Richard B. Kreckel)
Date: Fri, 02 Oct 2009 00:00:13 +0200
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <13436.1254430634@krein.leeds.ac.uk>
References: <31192.1253970592@krein.leeds.ac.uk>
	<4AC3D00D.9060406@ginac.de>	<2682.1254410478@krein.leeds.ac.uk>
	<4AC4CF6F.3070104@missouri.edu>
	<13436.1254430634@krein.leeds.ac.uk>
Message-ID: <4AC5266D.4090502@ginac.de>

Vladimir V. Kisil wrote:
>>>>>> On Thu, 01 Oct 2009 10:49:03 -0500, Stephen Montgomery-Smith <stephen at missouri.edu> said:
>     SMS> It will also be true for arbitrary x if a is an integer.
> 
> 	Good point! The third iteration of the patch is attached.
[...]
> +	if (x.info(info_flags::integer) || a.info(info_flags::integer)
> +		|| (x.info(info_flags::real) && a.info(info_flags::real)))
> +		return exp(x*a);

Maybe it is just too late, but I don't see the motivation for the "is x 
an integer" condition.

   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>


From kisilv at maths.leeds.ac.uk  Fri Oct  2 09:33:44 2009
From: kisilv at maths.leeds.ac.uk (Vladimir V. Kisil)
Date: Fri, 02 Oct 2009 08:33:44 +0100
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC5266D.4090502@ginac.de>
References: <31192.1253970592@krein.leeds.ac.uk> <4AC3D00D.9060406@ginac.de>
	<2682.1254410478@krein.leeds.ac.uk> <4AC4CF6F.3070104@missouri.edu>
	<13436.1254430634@krein.leeds.ac.uk> <4AC5266D.4090502@ginac.de>
Message-ID: <1854.1254468824@krein.leeds.ac.uk>

>>>>> On Fri, 02 Oct 2009 00:00:13 +0200, "Richard B. Kreckel" <kreckel at ginac.de> said:
    RK> Maybe it is just too late, but I don't see the motivation for
    RK> the "is x an integer" condition.

	Why not, if it is a correct substitution. Who know, may be as a
  result of some evaluation power of the exponents will becomes 2.

  Best wishes,
  Vladimir  
-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/


From stephen at missouri.edu  Fri Oct  2 14:11:51 2009
From: stephen at missouri.edu (Stephen Montgomery-Smith)
Date: Fri, 02 Oct 2009 07:11:51 -0500
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <1854.1254468824@krein.leeds.ac.uk>
References: <31192.1253970592@krein.leeds.ac.uk>
	<4AC3D00D.9060406@ginac.de>	<2682.1254410478@krein.leeds.ac.uk>
	<4AC4CF6F.3070104@missouri.edu>	<13436.1254430634@krein.leeds.ac.uk>
	<4AC5266D.4090502@ginac.de> <1854.1254468824@krein.leeds.ac.uk>
Message-ID: <4AC5EE07.6000809@missouri.edu>

Vladimir V. Kisil wrote:
>>>>>> On Fri, 02 Oct 2009 00:00:13 +0200, "Richard B. Kreckel" <kreckel at ginac.de> said:
>     RK> Maybe it is just too late, but I don't see the motivation for
>     RK> the "is x an integer" condition.
> 
> 	Why not, if it is a correct substitution. Who know, may be as a
>   result of some evaluation power of the exponents will becomes 2.

I think it is wrong to include "x is an integer."  Even 1^i (which is 
exp(0)^i) is not well defined (it can be any of e^(2 pi n) for all 
integers).




From kisilv at maths.leeds.ac.uk  Fri Oct  2 16:48:29 2009
From: kisilv at maths.leeds.ac.uk (Vladimir V. Kisil)
Date: Fri, 02 Oct 2009 15:48:29 +0100
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC5EE07.6000809@missouri.edu>
References: <31192.1253970592@krein.leeds.ac.uk> <4AC3D00D.9060406@ginac.de>
	<2682.1254410478@krein.leeds.ac.uk> <4AC4CF6F.3070104@missouri.edu>
	<13436.1254430634@krein.leeds.ac.uk>
	<4AC5266D.4090502@ginac.de> <1854.1254468824@krein.leeds.ac.uk>
	<4AC5EE07.6000809@missouri.edu>
Message-ID: <21991.1254494909@krein.leeds.ac.uk>

>>>>> On Fri, 02 Oct 2009 07:11:51 -0500, Stephen Montgomery-Smith <stephen at missouri.edu> said:
    SMS> I think it is wrong to include "x is an integer."  Even 1^i
    SMS> (which is exp(0)^i) is not well defined (it can be any of e^(2
    SMS> pi n) for all integers).

	Alright, here is the patch to stay on the safe side.

	Best wishes,
	Vladimir
-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/
-------------- next part --------------
--- inifcns_trans.cpp	2009-02-17 13:39:22.000000000 +0000
+++ patches/inifcns_trans.cpp	2009-10-02 15:45:17.000000000 +0100
@@ -99,9 +99,18 @@
 	return exp(GiNaC::real_part(x))*sin(GiNaC::imag_part(x));
 }
 
+static ex exp_power(const ex & x, const ex & a)
+{
+	if (a.info(info_flags::integer) || (x.info(info_flags::real) && a.info(info_flags::real)))
+		return exp(x*a);
+
+	return power(exp(x), a).hold();
+}
+
 REGISTER_FUNCTION(exp, eval_func(exp_eval).
                        evalf_func(exp_evalf).
                        derivative_func(exp_deriv).
+                       power_func(exp_power).
                        real_part_func(exp_real_part).
                        imag_part_func(exp_imag_part).
                        latex_name("\\exp"));

From kreckel at ginac.de  Sat Oct  3 23:53:18 2009
From: kreckel at ginac.de (Richard B. Kreckel)
Date: Sat, 03 Oct 2009 23:53:18 +0200
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC5EE07.6000809@missouri.edu>
References: <31192.1253970592@krein.leeds.ac.uk>	<4AC3D00D.9060406@ginac.de>	<2682.1254410478@krein.leeds.ac.uk>	<4AC4CF6F.3070104@missouri.edu>	<13436.1254430634@krein.leeds.ac.uk>	<4AC5266D.4090502@ginac.de>
	<1854.1254468824@krein.leeds.ac.uk> <4AC5EE07.6000809@missouri.edu>
Message-ID: <4AC7C7CE.8000705@ginac.de>

Hi!

Stephen Montgomery-Smith wrote:
> Vladimir V. Kisil wrote:
>>>>>>> On Fri, 02 Oct 2009 00:00:13 +0200, "Richard B. Kreckel" 
>>>>>>> <kreckel at ginac.de> said:
>>     RK> Maybe it is just too late, but I don't see the motivation for
>>     RK> the "is x an integer" condition.
>>
>>     Why not, if it is a correct substitution. Who know, may be as a
>>   result of some evaluation power of the exponents will becomes 2.

Actually, including "x is an integer" turns out to be correct. But we 
can do even better: it is sufficient to test if a is real.

Here is a proof. With arbitrary complex b:

     pow(exp(a),b) == exp(b*log(exp(a))

Since a is real, we know that exp(a) is real and positive. So 
log(exp(a))==a and exp(b*log(exp(a))==exp(b*a).  q.e.d.

I'll push a patch for the exp function and for doc/powerlaws.tex.

> I think it is wrong to include "x is an integer."  Even 1^i (which is 
> exp(0)^i) is not well defined (it can be any of e^(2 pi n) for all 
> integers).

That argument is confused. After all, we rewrite exp(2*Pi*I) -> 1.

   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>


From kreckel at ginac.de  Sun Oct  4 00:31:02 2009
From: kreckel at ginac.de (Richard B. Kreckel)
Date: Sun, 04 Oct 2009 00:31:02 +0200
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC7C7CE.8000705@ginac.de>
References: <31192.1253970592@krein.leeds.ac.uk>	<4AC3D00D.9060406@ginac.de>	<2682.1254410478@krein.leeds.ac.uk>	<4AC4CF6F.3070104@missouri.edu>	<13436.1254430634@krein.leeds.ac.uk>	<4AC5266D.4090502@ginac.de>	<1854.1254468824@krein.leeds.ac.uk>
	<4AC5EE07.6000809@missouri.edu> <4AC7C7CE.8000705@ginac.de>
Message-ID: <4AC7D0A6.9000707@ginac.de>

Hi!

I wrote:
> I'll push a patch for the exp function and for doc/powerlaws.tex.

Oh, it is all there in doc/powerlaws.tex!

This is another fine example where we saved an hour or so reading the 
documentation by spending a couple of days arguing back and forth.  :-)

   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>


From kreckel at ginac.de  Sun Oct  4 21:23:45 2009
From: kreckel at ginac.de (Richard B. Kreckel)
Date: Sun, 04 Oct 2009 21:23:45 +0200
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC7C7CE.8000705@ginac.de>
References: <31192.1253970592@krein.leeds.ac.uk>	<4AC3D00D.9060406@ginac.de>	<2682.1254410478@krein.leeds.ac.uk>	<4AC4CF6F.3070104@missouri.edu>	<13436.1254430634@krein.leeds.ac.uk>	<4AC5266D.4090502@ginac.de>	<1854.1254468824@krein.leeds.ac.uk>
	<4AC5EE07.6000809@missouri.edu> <4AC7C7CE.8000705@ginac.de>
Message-ID: <4AC8F641.6050203@ginac.de>

Hi!

I wrote:
> I'll push a patch for the exp function and for doc/powerlaws.tex.

Well, I didn't push it yet because it turns out that it interferes in 
surprising ways with mul::eval(). We used to have exp(x)/exp(x) -> 1 but 
that doesn't work any more because exp(x)^(-1) evaluates to exp(-x) 
first, resulting in exp(x)/exp(x) -> exp(x)*exp(-x).  :-(

Unless somebody comes up with a convincing idea how to fix eval() in the 
presence of pow(exp(x),a) -> exp(a*x) I'm not going to apply this patch.

Bye
   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>


From git at ginac.de  Sun Oct  4 22:14:13 2009
From: git at ginac.de (Jens Vollinga)
Date: Sun,  4 Oct 2009 22:14:13 +0200 (CEST)
Subject: [GiNaC-devel] [SCM] GiNaC -- a C++ library for symbolic
	computations branch, ginac_1-5, updated. release_1-4-0-214-g9fb1753
Message-ID: <20091004201413.49F9F5B4063@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, ginac_1-5 has been updated
       via  9fb17531da05d2959decc3856d03c71c0220b116 (commit)
      from  43d36593b9588b938a42a98f823c36c9f1ded088 (commit)

Those revisions listed above that are new to this repository have
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- Log -----------------------------------------------------------------
commit 9fb17531da05d2959decc3856d03c71c0220b116
Author: Jens Vollinga <jensv at nikhef.nl>
Date:   Sun Oct 4 22:15:13 2009 +0200

    Moved header includes to source files to avoid polluting the namespace
    for library users.

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

Summary of changes:
 ginac/parser/default_reader.tpl |    7 +++++++
 ginac/parser/parse_context.h    |    6 ------
 ginac/parser/parser.cpp         |    6 ++++++
 3 files changed, 13 insertions(+), 6 deletions(-)


hooks/post-receive
--
GiNaC -- a C++ library for symbolic computations


From fmaltey at nerim.fr  Sun Oct  4 22:14:47 2009
From: fmaltey at nerim.fr (Francois Maltey)
Date: Sun, 04 Oct 2009 22:14:47 +0200
Subject: [GiNaC-devel] Powers of exponents
In-Reply-To: <4AC8F641.6050203@ginac.de>
References: <31192.1253970592@krein.leeds.ac.uk>	<4AC3D00D.9060406@ginac.de>	<2682.1254410478@krein.leeds.ac.uk>	<4AC4CF6F.3070104@missouri.edu>	<13436.1254430634@krein.leeds.ac.uk>	<4AC5266D.4090502@ginac.de>	<1854.1254468824@krein.leeds.ac.uk>	<4AC5EE07.6000809@missouri.edu>
	<4AC7C7CE.8000705@ginac.de> <4AC8F641.6050203@ginac.de>
Message-ID: <4AC90237.9020207@nerim.fr>

Hello everybody,

I'm a new ginac user because I discover sage. So you might excuse my 
point of view if my arguments are out of ginac purpose. And this message 
isn't direct reponse for this patch.

// 1 //

I understand that ginac operates over complex analysis as the other 
computer algebra systems.

In this case it's very curious to write exp(u)^v == exp(u*v).
Fine choices of "branch cuts" may allow this point of view for a local 
study,
but it isn't usual mathematics for general purpose.

You understand I don't like the exp(u)^v == exp(u*v)

// 2 //

It' bad if exp(x)/exp(x) remains : sage reduces sin(x)/sin(x)  == 1 as 
usual.
I don't know the inner algorithms of ginac but I suppose that all 
function calls as sin(x) are seen as a new variable in the expression 
which is a fraction with a lot of variables, even if someones as sin(x) 
and cos(x) are linked together by cos(x)^2+sin(x)^2==1.

So exp(x)/exp(x) must be simplified in 1.

// 3 //

Look at sin(x) and cos(x).

Sometimes the user prefers the expanded formula with Tchebytchev polynomials
(cos(2x)+1)/(sin(2x)) == (2 cos(x)^2)/(2 sin(x) cos(x)) == cos(x)/sin(x) 
== cotan(x).

Othertimes the user wants to combine 2 cos(x)^2 into the (almost) linear 
form cos(2x)+1.
Computer algebra systems don't have any automatic transform
but the user calls the expand or the combine function for theses 
opposite purposes.

Calculus are similar with exp : both transforms exp(x)^2 <==> exp(2*x) 
are useful.

I observe that ginac respects algebraic user input :
by example there are very view transform with

x = 2*t/(1-t^2) ;
x.subs(t=x) == 4*t / (1 - (2*t/(1-t^2))^2)

Then the user calls expand, "simplify_fractions" or others functions if 
he wants an other form of this input.

power and exp functions might be in the same case :
exp(x)^2 remains exp(x)^2 and exp(2*x) remains exp(2*x).
Then an expand call translates exp(2*x) to exp(x)^2
and a combine (or an other name) translates back exp(x)^2 to exp(2*x)

If it does so, ginac respects also the user choice for the exp function 
as it does for the fractions.



From git at ginac.de  Sun Oct  4 22:34:15 2009
From: git at ginac.de (Richard B. Kreckel)
Date: Sun,  4 Oct 2009 22:34:15 +0200 (CEST)
Subject: [GiNaC-devel] [SCM] GiNaC -- a C++ library for symbolic
	computations branch, master, updated. release_1-4-0-200-g9b5d06b
Message-ID: <20091004203415.4A15A5B4063@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  9b5d06b34d3ee5f0ccd3c500be38fcdf61222956 (commit)
      from  ac235fa0a9285c055993bfa019896018db1817e6 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit 9b5d06b34d3ee5f0ccd3c500be38fcdf61222956
Author: Richard Kreckel <kreckel at ginac.de>
Date:   Sun Oct 4 22:30:45 2009 +0200

    Output LaTeX-symbols using \mathrm, instead of \mbox.
    
    Using \mathrm improves printing in complex formulae.
    One reason is that it scales in fractions. [by Vladimir Kisil]

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

Summary of changes:
 ginac/constant.cpp         |    6 +++---
 ginac/inifcns.cpp          |    4 ++--
 ginac/inifcns_gamma.cpp    |    2 +-
 ginac/inifcns_nstdsums.cpp |    6 +++---
 4 files changed, 9 insertions(+), 9 deletions(-)


hooks/post-receive
--
GiNaC -- a C++ library for symbolic computations


From git at ginac.de  Sun Oct  4 22:34:37 2009
From: git at ginac.de (Richard B. Kreckel)
Date: Sun,  4 Oct 2009 22:34:37 +0200 (CEST)
Subject: [GiNaC-devel] [SCM] GiNaC -- a C++ library for symbolic
	computations branch, ginac_1-5, updated. release_1-4-0-216-ge710763
Message-ID: <20091004203437.7BA4F5B4063@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, ginac_1-5 has been updated
       via  e710763e51b6fe11020bac880c44f426544471c2 (commit)
       via  71e1de972fd7f37d560427bffbb0f36215788d31 (commit)
      from  9fb17531da05d2959decc3856d03c71c0220b116 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit e710763e51b6fe11020bac880c44f426544471c2
Merge: 71e1de972fd7f37d560427bffbb0f36215788d31 9fb17531da05d2959decc3856d03c71c0220b116
Author: Richard Kreckel <kreckel at ginac.de>
Date:   Sun Oct 4 22:34:33 2009 +0200

    Merge branch 'ginac_1-5' of ssh://www.ginac.de/srv/git/ginac into ginac_1-5

commit 71e1de972fd7f37d560427bffbb0f36215788d31
Author: Richard Kreckel <kreckel at ginac.de>
Date:   Sun Oct 4 22:30:45 2009 +0200

    Output LaTeX-symbols using \mathrm, instead of \mbox.
    
    Using \mathrm improves printing in complex formulae.
    One reason is that it scales in fractions. [by Vladimir Kisil]

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

Summary of changes:
 ginac/constant.cpp         |    6 +++---
 ginac/inifcns.cpp          |    4 ++--
 ginac/inifcns_gamma.cpp    |    2 +-
 ginac/inifcns_nstdsums.cpp |    6 +++---
 4 files changed, 9 insertions(+), 9 deletions(-)


hooks/post-receive
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From jensv at nikhef.nl  Tue Oct  6 21:34:44 2009
From: jensv at nikhef.nl (Jens Vollinga)
Date: Tue, 06 Oct 2009 21:34:44 +0200
Subject: [GiNaC-devel] Upcoming GiNaC release
Message-ID: <4ACB9BD4.6090402@nikhef.nl>

Hi everybody,

I am finally going to make a 1.5.4 release soon (let's say next 
weekend). Are there any pending issues left?

Regards,
Jens


From jensv at nikhef.nl  Tue Oct  6 21:32:41 2009
From: jensv at nikhef.nl (Jens Vollinga)
Date: Tue, 06 Oct 2009 21:32:41 +0200
Subject: [GiNaC-devel] GiNaC and polylogarithms
In-Reply-To: <20090908204036.GA7244@nanos8.pcteor1.mi.infn.it>
References: <20090908204036.GA7244@nanos8.pcteor1.mi.infn.it>
Message-ID: <4ACB9B59.1080106@nikhef.nl>

Hi,

sorry for the late reply.

Emanuele Bagnaschi schrieb:
> First, G-functions currently evaluate numerically only for real
> arguments y >= 0. 

yes. But I have my doubts that "improving" this is really helpful for 
practice.

> Secondly, in the tutorial is written that there's no support 
> for compiling expressions containing polylogarithms to C function pointers.

True. This is badly missing. GiNaC should be able to generate a C 
function that numerically evaluates a specific polylog in double 
precision and whose name would be used in expression output. One reason 
for not having implemented this yet is a principle problem of the code, 
see below.

> Finally, I see that there are some "TODO" comments in inifcns_nsdsums.cpp which describe missing features. 

Yes, but a lot of them are not that urgent, I think.

> I'm also open to any other suggestions.
> All comments are welcome.

Two more issues (which are the most urgent in this):

- Multiple polylogs with roots of unity as arguments (x1,x2,...) produce 
for certain weights (m1,m2,...) wrong numeric results. There is still a 
bug in the transformations. I would have to look a while for the 
details. But while it is probably of no consequence for physics 
applications, it is still a bad bug and needs to be fixed.

- The code is badly written. It mixes purely algebraic operations 
(transformations) with numerics while using a (prematurely ...) 
optimized representation of the arguments. This had and has three 
consequences: bugs like above are very hard to catch, generating C 
functions for compiled expressions is very difficult because the formula 
  used in the end for the numerics is not available to the outside as a 
whole (i.e. other functions managing the expression compilation), and 
thirdly the functionality of just asking a polylog what its so and so 
transformation would yield is not available to the user (there are other 
nice math packages that offer this).

Regards,
Jens


From kisilv at maths.leeds.ac.uk  Tue Oct  6 22:07:49 2009
From: kisilv at maths.leeds.ac.uk (Vladimir V. Kisil)
Date: Tue, 06 Oct 2009 21:07:49 +0100
Subject: [GiNaC-devel] Upcoming GiNaC release
In-Reply-To: <4ACB9BD4.6090402@nikhef.nl>
References: <4ACB9BD4.6090402@nikhef.nl>
Message-ID: <24749.1254859669@krein.leeds.ac.uk>

		Dear Jens,

		The part of my patch from

http://www.ginac.de/pipermail/ginac-devel/2009-September/001656.html

  which deals with positivity of adds and muls was not applied, I do not
  know either it is forgotten or was not approved.

  Best wishes,
  Vladimir
-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/


From emanueleb at pcteor1.mi.infn.it  Sun Oct 11 23:25:55 2009
From: emanueleb at pcteor1.mi.infn.it (Emanuele Bagnaschi)
Date: Sun, 11 Oct 2009 23:25:55 +0200
Subject: [GiNaC-devel] GiNaC and polylogarithms
In-Reply-To: <4ACB9B59.1080106@nikhef.nl>
References: <20090908204036.GA7244@nanos8.pcteor1.mi.infn.it>
	<4ACB9B59.1080106@nikhef.nl>
Message-ID: <20091011212555.GA6152@nanos8.pcteor1.mi.infn.it>

On 21:32 Tue 06 Oct     , Jens Vollinga wrote:
> Emanuele Bagnaschi schrieb:
> >First, G-functions currently evaluate numerically only for real
> >arguments y >= 0.
> 
> yes. But I have my doubts that "improving" this is really helpful
> for practice.

I find your comment extremely interesting, since I was specifically
asked to look how to evaluate G-functions in the complex field.  Do you
think that the extension is naive because of the "scaling relation"?
Or there is something else behind your comment?

> 
> [...]
> 

I see that there is really a lot of work to do but I'm willing to
contribute to this project and improve the status of GiNaC with this
regard. I'm really interested, even at the personal level. In fact
I've searched for years for an interesting open source project to
start contributing to.

However I won't be free to focus on this matter at least until the
21st of October, due to some major university duties. In the meanwhile
I will try to get acquainted with the existing GiNaC code.

Best regards.
-- 
Emanuele A. Bagnaschi


From git at ginac.de  Sun Oct 11 23:26:42 2009
From: git at ginac.de (Richard B. Kreckel)
Date: Sun, 11 Oct 2009 23:26:42 +0200 (CEST)
Subject: [GiNaC-devel] [SCM] GiNaC -- a C++ library for symbolic
	computations branch, ginac_1-5, updated. release_1-4-0-217-gc7299e5
Message-ID: <20091011212642.C2CCF5B4067@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, ginac_1-5 has been updated
       via  c7299e51d5ecf61b5d85bdfeb9a2db536abf18bb (commit)
      from  e710763e51b6fe11020bac880c44f426544471c2 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit c7299e51d5ecf61b5d85bdfeb9a2db536abf18bb
Author: Richard Kreckel <kreckel at ginac.de>
Date:   Sun Oct 11 23:19:21 2009 +0200

    Add mul::info() and add::info() support for numeric info_flags.
    
    This way, GiNaC knows that the sum or product of a number of positive
    expressions is again a positive expression. [by Vladimir Kisil]

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

Summary of changes:
 ginac/add.cpp   |   12 ++++++++++++
 ginac/flags.h   |    2 +-
 ginac/mul.cpp   |   12 ++++++++++++
 ginac/power.cpp |    2 ++
 4 files changed, 27 insertions(+), 1 deletions(-)


hooks/post-receive
--
GiNaC -- a C++ library for symbolic computations


From git at ginac.de  Sun Oct 11 23:26:42 2009
From: git at ginac.de (Richard B. Kreckel)
Date: Sun, 11 Oct 2009 23:26:42 +0200 (CEST)
Subject: [GiNaC-devel] [SCM] GiNaC -- a C++ library for symbolic
	computations branch, master, updated. release_1-4-0-201-g5631205
Message-ID: <20091011212643.27F685B4065@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  5631205a455c42a32ce9d50b6c99df0f1ad6b4e7 (commit)
      from  9b5d06b34d3ee5f0ccd3c500be38fcdf61222956 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit 5631205a455c42a32ce9d50b6c99df0f1ad6b4e7
Author: Richard Kreckel <kreckel at ginac.de>
Date:   Sun Oct 11 23:19:21 2009 +0200

    Add mul::info() and add::info() support for numeric info_flags.
    
    This way, GiNaC knows that the sum or product of a number of positive
    expressions is again a positive expression. [by Vladimir Kisil]

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

Summary of changes:
 ginac/add.cpp   |   12 ++++++++++++
 ginac/flags.h   |    2 +-
 ginac/mul.cpp   |   12 ++++++++++++
 ginac/power.cpp |    2 ++
 4 files changed, 27 insertions(+), 1 deletions(-)


hooks/post-receive
--
GiNaC -- a C++ library for symbolic computations


From kreckel at ginac.de  Sun Oct 11 23:34:34 2009
From: kreckel at ginac.de (Richard B. Kreckel)
Date: Sun, 11 Oct 2009 23:34:34 +0200
Subject: [GiNaC-devel] Upcoming GiNaC release
In-Reply-To: <24749.1254859669@krein.leeds.ac.uk>
References: <4ACB9BD4.6090402@nikhef.nl> <24749.1254859669@krein.leeds.ac.uk>
Message-ID: <4AD24F6A.9080603@ginac.de>

Dear Vladimir,

Vladimir V. Kisil wrote:
> 		The part of my patch from
> 
> http://www.ginac.de/pipermail/ginac-devel/2009-September/001656.html
> 
>   which deals with positivity of adds and muls was not applied, I do not
>   know either it is forgotten or was not approved.

I've talked with Jens about it and, as a result, pushed it in. In the 
future, could you, please, submit git-style commented patches of 
individual topics? (Best give git a try. It's a fantastic system!) 
Thanks in advance!

    -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>


From kisilv at maths.leeds.ac.uk  Sun Oct 11 23:33:12 2009
From: kisilv at maths.leeds.ac.uk (Vladimir V. Kisil)
Date: Sun, 11 Oct 2009 22:33:12 +0100
Subject: [GiNaC-devel] Upcoming GiNaC release
In-Reply-To: <4AD24F6A.9080603@ginac.de>
References: <4ACB9BD4.6090402@nikhef.nl> <24749.1254859669@krein.leeds.ac.uk>
	<4AD24F6A.9080603@ginac.de>
Message-ID: <8819.1255296792@krein.leeds.ac.uk>

>>>>> On Sun, 11 Oct 2009 23:34:34 +0200, "Richard B. Kreckel" <kreckel at ginac.de> said:
    RK> Best give git a try. It's a  fantastic system!
	
	I will try to learn it on the next occasion.

	Best wishes,
	Vladimir
-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/