February 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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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-620-g8643e3cb
by Richard B. Kreckel 17 Feb '19

17 Feb '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 8643e3cba4f229faba5d1aeb9a7b31ba609f81fb (commit) from 2d33e40249cafcb9a0547c282e6e6790a480e81b (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 8643e3cba4f229faba5d1aeb9a7b31ba609f81fb Author: Richard Kreckel <kreckel(a)ginac.de> Date: Sun Feb 17 20:43:28 2019 +0100 Convert YAPTU to Python3. It should now work with python2 and python3. ----------------------------------------------------------------------- Summary of changes: scripts/yaptu.py | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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Release 1.7.5
by Richard B. Kreckel 17 Feb '19

17 Feb '19

Hi, A new GiNaC version has just been released. The changes are: * Add Markowitz-ordered Gaussian elimination. * Avoid un-normal zeros in matrix::solve(). * Accept exprseq arguments in lsolve(eqns, vars). * Add overload of matrix::rank(solve_algo). * Fix case in G_do_hoelder with real x values which are not cl_R. * Fix an elusive bug in expairseq/add ctor, introduced in 1.7.0. Happy hacking! -richy.

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[SCM] GiNaC -- a C++ library for symbolic computations tag, release_1-7-5, created. release_1-4-0-619-g2d33e402
by Richard B. Kreckel 17 Feb '19

17 Feb '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 tag, release_1-7-5 has been created at 2d33e40249cafcb9a0547c282e6e6790a480e81b (commit) - Log ----------------------------------------------------------------- commit 2d33e40249cafcb9a0547c282e6e6790a480e81b Author: Richard Kreckel <kreckel(a)ginac.de> Date: Sun Feb 17 12:13:10 2019 +0100 Finalize 1.7.5 release. ----------------------------------------------------------------------- hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-619-g2d33e402
by Richard B. Kreckel 17 Feb '19

17 Feb '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 2d33e40249cafcb9a0547c282e6e6790a480e81b (commit) from 3ea59519b3fa572a2aba7b8540b336dcb2924262 (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 2d33e40249cafcb9a0547c282e6e6790a480e81b Author: Richard Kreckel <kreckel(a)ginac.de> Date: Sun Feb 17 12:13:10 2019 +0100 Finalize 1.7.5 release. ----------------------------------------------------------------------- Summary of changes: AUTHORS | 44 +++++++++++++++++++++++++------------------- NEWS | 8 ++++++++ ginac/version.h | 6 +++--- 3 files changed, 36 insertions(+), 22 deletions(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-618-g3ea59519
by Richard B. Kreckel 16 Feb '19

16 Feb '19

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