- GiNaC-list - ginac.de

How can I build an expression one character at a time?
by Roger Gordon 08 Jan '13

08 Jan '13

Hi guys, I recently started using ginac, and one thing I couldnt figure out from the tutorial is how can I make an expression one piece at a time. So if I wanted to build an expresison out of a list like x,=,5,*,4 I imagine doing something like ex expr; expr.append(x); expr.append(==); expr.append(5); expr.append(4); I understand the numbers are numerics, and x would be a symbol, but I dont know what the operators would be ( * / + - ). Does anyone how I can do this? Does this even make any sense to you? Thanks for any replies! R. Gordon

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Simple question about how to solve for a simple non-linear system of equations.
by Zach 06 Jan '13

06 Jan '13

Hi guys I know this is a really basic question but after looking at the tutorial and reference I couldn't quite figure out how to solve a nonlinear system of equations. (If this is even possible, I dont know). I have this: lst eqns, vars; > > eqns = D==pow(T,2); > > vars =T; > > ex L = lsolve(eqns,vars); > But lsolve (I guess the l for linear makes it obvious) cannot solve this nonlinear function. Is there another way I can accomplish this? Then I could do something like: ex ans = L.subs(lst(D==3)); like I would for a linear? Is this even possible? Thanks for any answer! Ginac is a great tool for me so far!

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Variable Isolation
by David Narvaez 17 Dec '12

17 Dec '12

Hi all, Is there a ready-to-use method to isolate a variable in an expression? At least for first and second degree polynomials in at most two variables. David E. Narvaez

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Compiled GiNAC lib for MSVC failed in debug mode
by Christiand 13 Dec '12

13 Dec '12

Hi All, I have successfully compiled GiNAC for MSVC. I compiled GiNAC as static library (*.lib). I works fine under release mode, but fails in debug mode. Does anyone experience same thing ? Thank before for your attention. ~ Christiand ~

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Ginac compile with MSVC
by Rheinländer 13 Dec '12

13 Dec '12

Hi, the current version of GiNaC requires a new hack to make it work with MSVC. The problem is lst::info(). It is never called when GiNaC is compiled with MSVC, instead, basic::info() gets called which leads to exceptions being thrown by code like: if (!eqns.info(info_flags::list)) { throw(std::invalid_argument("lsolve(): 1st argument must be a list or an equation")); The only work-around I could find was to move the definition of lst::info() from the .cpp file to the .h file (please don't ask me why this should make a difference). I know it's a stupid hack, but in any case, I attach the modified lst.h and lst.cpp in case you want to include it in a future release of GiNaC. Jan

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set_TeX_name() ?
by Dale Lukas Peterson 10 Dec '12

10 Dec '12

I see that there is a set_name method in the symbol class and was wondering if there is a reason there is no set_TeX_name() method? I have a situation where I would like to declare a number of symbols, all using the default constructor, but then would like to set the TeX string of these symbols later. It seems like this implementation would work fine: void set_TeX_name(const std::string & n) { TeX_name = n; } Attached is a patch, if this implementation seems reasonable. I'm not sure whether TeX_name should be mutable or not, it seems like perhaps it also should be? Thanks, Luke -- “People call me a perfectionist, but I'm not. I'm a rightist. I do something until it's right, and then I move on to the next thing.” ― James Cameron

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Empty brackets in compiled C code.
by Zach 07 Dec '12

07 Dec '12

Hi guys. Finally, with the help of those on this mailing list I was able to compile the lenet5 demo into c. But at first I was getting a few of these errors from the compiled C code: /home/refinedcode/Development/lush/packages/gblearn2/demos/C/lenet5_fprop.c:327:278: > error: expected expression before ‘)’ token > So i opened up the C code and found that all the errors pointed towards this one line: (L3_19__x_)->Vtbl->M_net_cscscf(L3_19__x_, L2_1_image_height, > L2_2_image_width, L2_3_ki0, L2_4_kj0, L2_13_table0, L2_5_si0, L2_6_sj0, > L2_7_ki1, L2_8_kj1, L2_14_table1, L2_9_si1, L2_10_sj1, > ((()((((double)(L2_1_image_height-((L2_3_ki0)-1)))/((double)L2_5_si0))-((L2_7_ki1)-1)))/(()L2_9_si1)), > ((()((((double)(L2_2_image_width-((L2_4_kj0)-1)))/((double)L2_6_sj0))-((L2_8_kj1)-1)))/(()L2_10_sj1)), > L_Tmp20, L2_12_output_size, L1_net_param); > > As you can see there are some empty brackets that have caused these errors. It wasn't a big deal to me as removing the empty brackets fixed the problem and it ran fine but is there somewhere I should post this? I don't assume anyone else has seen this before? Maybe im doing something wrong that caused it. If anyone wants I can post more details about it but I doubt it would be anyone's priority. Thanks for helping me with my questions by the way! Lush works very well!

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How to init ex with a string
by 东光 29 Nov '12

29 Nov '12

Who can tell me how to init ex with a string ? Thank you very much!

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Problem in factor
by Ulrich Loup 20 Nov '12

20 Nov '12

Hello list, we use GiNaC::factor in our program to factorize univariate and multivariate polynomials. This works quite well on our instances, however we encounter strange segfaults sometimes, e.g. in the following cases: factor(-5474155567807987/200000000000000+174247781/20000000*x^2-1989199947807987/200000000000000*x); factor(-5474155567807987/20000000000000+174247781/10000000*x^2-1989199947807987/200000000000000*x); factor(-5474155567807987/200000000000000+174247781/1000000*x^2-1989199947807987/200000000000000*x); factor(-5474155567807987/200000000000000+174247781/10*x^2-1989199947807987/200000000000000*x); factor(-5474155567807987/200000000000000+174247781/2*x^2-1989199947807987/200000000000000*x); factor(-5474155567807987+174247781/10000000*x^2-1989199947807987/200000000000000*x); factor(174247781/10000000*x^2-1989199947807987/200000000000000*x); factor(174247781*x^2-1989199947807987/200000000000000*x); The latter calls are just modifications of the original first call, but all of them fail. I did not manage to pinpoint a commonality which could give a clue to the actual cause of the error. With a debugger, we traced the error to a call to CLN's * operator (in factor.cpp:1512), in particular, the method the<cl_I>( ... ). However, the actual problem might already be in GiNaC. I suspect, there is a problem with computing the content of the input by GiNaC::unitcontprim 10 lines above the error occurrence, but I'm not sure. We used ginac-1.6.2 and cln-1.3.2-r1 on a Gentoo Linux machine. Does anyone have an idea what is going wrong here? Best regards, Ulrich.

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Codeblocks - Fedora 17
by Alessio Nava 16 Oct '12

16 Oct '12

I'm trying to compile one of the sample using Codeblocks with gcc 4.7.2 on Fedora 17. The file compiles fine using the terminal with the additional flags as stated in the documentation. How can I do the same in Codeblocks? Even if I set those flags in the build options I get hundreds of undefined references. Same happens with netscape. -- Alessio Nava *EvaluatorXY- Maths Analysis Software * * * https://sites.google.com/site/alessionavasdeveloperhub/buy-evaluatorxy

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