February 2002 - GiNaC-list

Problems with expand()
by Tatiana Zolo 05 Mar '02

05 Mar '02

We have a few questions about GinaC's behaviour. For our purposes, it would be useful to have a slightly more general form of expand that takes care of non-ambiguous iterated exponentials, as in the case (2^x)^3 which we would like to see in the form 2^(3*x) or even 8^x We understand that there are cases when this should not be done automatically, but we believe that this is an instance when there is no harm in simplifying since 2 is a positive real number and there is no question of complex numbers being involved. A "real" version of expand would be very useful for us. Do you plan to add these features to a future release of GiNaC? Thank you very much. Best wishes Alessandro Zaccagnini Tatiana Zolo purrs developers, at the University of Parma, Italy

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Problem with subs
by Tatiana Zolo 28 Feb '02

28 Feb '02

We do not understand how subs works in some cases: we tried the following ginsh session > p=x+1; 1+x > subs(p,x==k-1); k > subs(p,x==x-1); -1+x > subs(p,x==x-2); -1+x > subs(p,x==x^2-1); x^2 > subs(p,x==x^2); 1+x^2 so, apparently, subs is sometimes wrong. We couldn't find anything in the documentation to explain this fact. Thank you very much. Best wishes Alessandro Zaccagnini Tatiana Zolo purrs developers, at the University of Parma, Italy

2 1

Problems with subs
by Tatiana Zolo 28 Feb '02

28 Feb '02

We do not understand how subs works in some cases: we tried the following ginsh session > p=x+1; 1+x > subs(p,x==k-1); k > subs(p,x==x-1); -1+x > subs(p,x==x-2); -1+x > subs(p,x==x^2-1); x^2 > subs(p,x==x^2); 1+x^2 so, apparently, subs is sometimes wrong. We couldn't find anything in the documentation to explain this fact. Thank you very much. Best wishes Alessandro Zaccagnini Tatiana Zolo purrs developers, at the University of Parma, Italy

1 0

Problem with expand()
by Tatiana Zolo 28 Feb '02

28 Feb '02

We have a few questions about GinaC's behaviour. For our purposes, it would be useful to have a slightly more general form of expand that takes care of non-ambiguous iterated exponentials, as in the case (2^x)^3 which we would like to see in the form 2^(3*x) or even 8^x We understand that there are cases when this should not be done automatically, but we believe that this is an instance when there is no harm in simplifying since 2 is a positive real number and there is no question of complex numbers being involved. A "real" version of expand would be very useful for us. Do you plan to add these features to a future release of GiNaC? Thank you very much. Best wishes Alessandro Zaccagnini Tatiana Zolo purrs developers, at the University of Parma, Italy

1 0

collect TeX output
by Christophe TROESTLER 15 Feb '02

15 Feb '02

Hi, It seems that GiNaC, when (for example) collecting expressions and then printing them to LaTeX adds some braces in additions to parentheses. For example symbol x("x"), y("y"), t("t"); ex e = x*t + y*t; collect(e,t).print(GiNaC::print_latex()); ouputs t {(y+x)} Is there any way (an option?) to remove the extra braces? Indeed, they force TeX NOT to BREAK the expression (i.e., it must fit on a single line) which is problematic when the expression is long. Thanks, ChriS

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