May 2019 - GiNaC-devel

evalf() on cube roots
by Jan Rheinländer 21 Sep '19

21 Sep '19

Picking up this old thread... I would like to submit a patch that allows choosing the convention for negative cube roots between the solution on the principal branch and the real-valued solution. That is, in the cln library, file complex/transcendental/cl_C_expt_C.cc I would like to handle the following case separately: y rational and y ratio m/n x rational and x < 0 n odd What about introducing a flag called (e.g.) cln::cl_odd_roots_of_rationals_real (similar to cln::cl_inhibit_floating_point_underflow)? If the flag is false (default), the above case evaluates to exp(log(x) * y) as before If the flag is true, it evaluates to (-1)^m * (-x)^(m/n) Would such a patch be acceptable? Greetings, Jan Rheinländer Am 02.08.2015 um 21:55 schrieb Richard B. Kreckel: > On 08/02/2015 08:59 PM, Jan Rheinländer wrote: >>> There isn't. GiNaC, like almost all other systems, returns the solution >>> on the principal branch, compatible with exp(log(-1)/3). >> I suppose there is some excellent mathematical reason for this... > Actually, there isn't. Branch cuts are a matter of convention. > Nothing more but also nothing less. > >> but for >> me it means that I can't use GiNaC to verify Cardano's formula for a >> cubic function: >> >>> x = (-1 - sqrt(2))^(1/3) + (-1 + sqrt(2))^(1/3); >> (-1-sqrt(2))^(1/3)+(-1+sqrt(2))^(1/3) >> >>> evalf(x^3 + 3 * x + 2); >> 3.3544445609126528848+8.9073474964875349776*I >> >> Surely there must be a way to verify such a formula in GiNaC??? > It should be straightforward to replace such rational expressions by the > form you want them to be in before calling evalf(), using techniques > such as these: <http://www.ginac.de/FAQ.html#advanced> > > Cheers > -richy.

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remove_dirac_ONE() and documentation patches
by Vladimir V. Kisil 09 Jun '19

09 Jun '19

Dear All, I am sending three patches for consideration. First two add some details to the GiNaC tutorial. The third one replaces remove_dirac_ONE() from the clifford.cpp. Currently remove_dirac_ONE() uses exceptions in normal operation to terminate a chain of recurrent calls. Some people would say that exceptions are evil, but this did not cause problems until I try to make a port for another evil---Windows. The exceptions in remove_dirac_ONE() terminated a Qt Windows application although the same code smoothly run under Linux. Thus I re-write remove_dirac_ONE() without exceptions. The signature of the method has to change, but a user may not notice this in the first approximation. Some respective alterations to the tutorial and the check suit are made 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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Patch multiple zeta values
by Stefan Weinzierl 04 Jun '19

04 Jun '19

Dear all, attached are two patches related to https://www.ginac.de/pipermail/ginac-list/2019-May/002265.html https://www.ginac.de/pipermail/ginac-list/2019-May/002266.html The first patch fixes the segmentation fault, the second patch improves the performance. Best wishes, Stefan

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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-628-g393c7d57
by Richard B. Kreckel 03 May '19

03 May '19

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 393c7d5716ae5bb76ce2f518dfd52f27b1bc6414 (commit) from f7884835d397de85e648d1957c058b7d4c0948ba (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 393c7d5716ae5bb76ce2f518dfd52f27b1bc6414 Author: Richard Kreckel <kreckel(a)ginac.de> Date: Fri May 3 21:14:20 2019 +0200 [DOC] Change library order in tutorial example. Some systems care about library ordering: Dependent libraries must be linked last. Let's link with -lginac before -lcln in the example so it will work on any system, even on Windows. ----------------------------------------------------------------------- Summary of changes: doc/tutorial/ginac.texi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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