May 2015 - GiNaC-list

Release 1.6.4
by Richard B. Kreckel 08 May '15

08 May '15

Hi, A new GiNaC release is out and available. These are the changes: * Fixed pow(+(...),2).expand() where the sum contained roots of rationals. * Various improvements for info(info_flags::nonnegative). * Make power::expand() (x*p)^c -> x^c * p^c, if p>0. * Fixed normal() where nested functions occur multiple times. * Add optional explicit derivatives to functions and use it in abs(), imag_part(), real_part(). * Evaluate abs(z)^(2n) -> z^n * conjugate(z)^n. Happy hacking -richy. -- Richard B. Kreckel <http://in.terlu.de/~kreckel/>

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Bug in expand
by Isuru Fernando 07 May '15

07 May '15

Hi, I modified the first benchmark at http://www.ginac.de/csSC-0004015.pdf to, e = expanded value of (a0 + a1 + sqrt(3)*a2 + sqrt(3)*a3 + ... + sqrt(3)*a(n-1))^2 in e, substitute a0 with -sqrt(3)*a2 - sqrt(3)*a3 - ... - sqrt(3)*a(n-1) expand e again to obtain a1^2 For n = 4, I get, -3*a3^2+2*3*a2^2+a1^2-6*a2^2+3*a3^2 Or 3*a3^2-3*a2^2-3*a3^2+a1^2+3*a2^2 which is true, but not the expression I expected. Why are the terms 3*a2^2 and -3*a2^2, not canceled out immediately? Also a term like 2*3*a2^2 means there is some bug right? I am using ginac-1.6.3 on Ubuntu 14.10 with gcc-4.9.1. I am attaching the sample program. Isuru Fernando

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compile_ex with more than two symbols in the expression
by William Silva 01 May '15

01 May '15

Dear all, Is there a way to use "compile_ex" with more than 2 free variables? I am generating several expressions using .diff() and would like to compile them into C functions and attach function pointers. Using the .subs() method is too slow for my code. Unfortunately my expressions contain more than just two symbolic variables. Ideally I would love to have a FUNCP_nP typedef that can accept a list or array of n symbolic variables and use a compile_ex function that accepts an lst of the symbols. I noticed that the FUNCP_CUBA typedef sort of does this, but I am not sure how to access the compiled function. Any help or pointers would be greatly appreciated! Best, Will S.

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