February 2015 - GiNaC-devel

04 Jun '15

Hi, is there any reason not to define the derivative of the built-in abs() function as either abs(x)/x or csgn(x) ? Currently it has not derivative defined at all. Regards, Jan

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compile_ex with HAVE_LIBDL with cmake build system
by Martin Vala 14 Apr '15

14 Apr '15

Dear ginac dev, i would like to use function compile_ex and it is not possible to set using cmake build system. I added some cmake configuration and all changes are in tarball http://alice.saske.sk/mvala/ginac/ginac-1.6.3.tar.bz2 Can you add this to 1.6.4? It would help me a lot. Thanks Ciao Martin

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Revised patch: Power transformation for real base and positive exponent
by Vladimir V. Kisil 22 Mar '15

22 Mar '15

Dear All, I am attaching the revised patch to power::expand(), which make the transformation: (x*p)^c --> x^c * p^c, if p>0 and c is real This seems to be helpful in many cases. A corresponding check is added as well. Best wishes, Vladimir -- Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Transformations http://goo.gl/EaG2Vu Software: Geometry of cycles http://moebinv.sourceforge.net/

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test
by Richard B. Kreckel 15 Feb '15

15 Feb '15

please ignore

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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-443-g1994570
by git＠ginac.de 08 Feb '15

08 Feb '15

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 1994570795185f89cc848843cc53664740d20fa0 (commit) via aa2485821e68ea5f627d5753b41245a4cbd62fe3 (commit) from fb9800befac02abddc754d051501ec446ae2b9bf (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 1994570795185f89cc848843cc53664740d20fa0 Author: Vladimir V. Kisil <kisilv(a)maths.leeds.ac.uk> Date: Sun Feb 8 20:53:55 2015 +0100 Fixing index in tutorial. The index entry for clifford::get_metric() did not work, change it to get_metric(). Signed-off-by: Vladimir V. Kisil <kisilv(a)maths.leeds.ac.uk> commit aa2485821e68ea5f627d5753b41245a4cbd62fe3 Author: Vladimir V. Kisil <kisilv(a)maths.leeds.ac.uk> Date: Sun Feb 8 20:50:51 2015 +0100 Explicit derivation of functions. Some function cannot be cleanly differentiated through the chain rule. For example, it is natural to define derivative of the absolute value as (abs(f))'=(f'*f.conjugate()+f*f'.conjugate())/2/abs(f) This patch adds a possibility to define derivatives of functions in this way. In particular the derivative of abs(), Order(), real_part(), imag_part() and conjugate() are defined. For example, conjugate of a derivative with respect of a real symbol If x is real then U.diff(x)-I*V.diff(x) represents both conjugate(U+I*V).diff(x) and conjugate((U+I*V).diff(x)) Thus in this patch we use the rule conjugate(f)'=conjugate(f') for a derivative with respect to the real symbol. Signed-off-by: Vladimir V. Kisil <kisilv(a)maths.leeds.ac.uk> ----------------------------------------------------------------------- Summary of changes: check/exam_inifcns.cpp | 66 +++++++++++++++++++++++++++++++++++++++++++++++++ doc/tutorial/ginac.texi | 28 ++++++++++++++++++--- ginac/function.cppy | 33 +++++++++++++++++++++---- ginac/function.hppy | 6 +++++ ginac/function.py | 2 +- ginac/inifcns.cpp | 54 +++++++++++++++++++++++++++++++++++++++- 6 files changed, 178 insertions(+), 11 deletions(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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Micro patch in tutorial
by Vladimir V. Kisil 07 Feb '15

07 Feb '15

Dear All, Another micro patch for tutorial. The index entry for clifford::get_metric() did not work, change it to get_metric(). Best wishes, Vladimir -- Vladimir V. Kisil email: kisilv(a)maths.leeds.ac.uk www: http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Transformations http://www.worldscientific.com/worldscibooks/10.1142/p835

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Implicit derivation of functions (re-submission)
by Vladimir V. Kisil 02 Feb '15

02 Feb '15

Dear All, I am resending the patch for implicit derivation of functions. Quote from the previous submission: http://www.ginac.de/pipermail/ginac-devel/2013-November/002053.html " I wish to propose another GiNaC extension. Consider function abs(). Since it can be presented as abs(z)=sqrt(z*z.conjugate()), the derivative of abs(f) may be calculated as (abs(f))'=(f'*f.conjugate()+f*f'.conjugate())/2/abs(f) However, this formula cannot be packed into the present GiNaC code, since it only knows about the chain rule. Thus, the patch adds a possibility to define derivatives of functions in some general expression. In particular, the above derivative of abs() is defined. Example: cout << abs(log(z)).diff(z) << endl; // (before) -> D[0](abs)(log(z))*z^(-1) // (now) -> 1/2*(z^(-1)*conjugate(log(z))+log(z)*conjugate(z)^(-1))*abs(log(z))^(-1) " This issue independently appeared in this discussion: http://www.ginac.de/pipermail/ginac-devel/2014-April/002106.html If it is not included in the core code, then a user need to redefine the entire GiNaC function class to have this feature. Best wishes, Vladimir -- Vladimir V. Kisil email: kisilv(a)maths.leeds.ac.uk -- www: http://maths.leeds.ac.uk/~kisilv/

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