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Computation problems

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	Computation problems by xlogo :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message Hello, I encounter a new problem with computation Here is my code: \documentclass[10pt]{article} \usepackage{tikz,pgf} \pagestyle{empty} \begin{document} \begin{tikzpicture} \draw [->] (-4,0)--(4,0); \foreach \x in {-3.6,-2.4,...,3.6} \draw[xshift=\x cm] (0,-2pt) -- (0,2pt) node [above] {\x}; \end{tikzpicture} \end{document} I know it's easy to draw this axis writing: \foreach \x in {-3.6 -2.4 -1.2 0 1.2 2.4 3.6} What interests me is if this computation problem is a bug and if it is possible to solve it in a near future. Or is this approximation with mathematical expression is part of pgf and pdf features and cannot be solved? Thanks in advance, Best regards Loïc ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ pgf-users mailing list pgf-users@... https://lists.sourceforge.net/lists/listinfo/pgf-users
	Re: Computation problems by Mark Wibrow-2 :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message 2008/7/22 Loïc <xlogo@...>: > > > What interests me is if this computation problem is a bug and if it is > possible to solve it in a near future. Or is this approximation with > mathematical expression is part of pgf and pdf features and cannot be > solved? > In this case, the foreach loop is actually using native TeX arithmetic. As is pointed out in the manual, TeX is not good with numbers that are not multiples of 2^-n. This can be seen with a simple example: \newdimen\mydimen \mydimen=-3.6pt \advance\mydimen by1.2pt Unfortunately there isn't a lot that can be done about it currently, so the ``long hand'' method is really the only option. Sorry Mark ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ pgf-users mailing list pgf-users@... https://lists.sourceforge.net/lists/listinfo/pgf-users
	Re: Computation problems by Mark Wibrow-2 :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message 2008/7/22 Mark Wibrow <m.wibrow@...>: > > \newdimen\mydimen > \mydimen=-3.6pt > \advance\mydimen by1.2pt > I missed out the line \the\mydimen This gives -2.40001pt on my system. -Mark ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ pgf-users mailing list pgf-users@... https://lists.sourceforge.net/lists/listinfo/pgf-users
	Re: Computation problems by xlogo :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message Many thanks for your answer. I explain why it's important for me: I have written a PGF/TikZ export for the dynamic geometry software called GeoGeBra (http://www.geogebra.org) and I'm finalizing it. As I explain before here on the list: http://www.nabble.com/Plotting-Problem-to18545611.html The fact that TeX arithmetic isn't very good makes me think that to plot functions, it's better to use the GnuPlot method than the native plot command. Am I right? Loïc Le mardi 22 juillet 2008 à 17:19 +0100, Mark Wibrow a écrit : > 2008/7/22 Mark Wibrow <m.wibrow@...>: > > > > \newdimen\mydimen > > \mydimen=-3.6pt > > \advance\mydimen by1.2pt > > > > I missed out the line > > \the\mydimen > > This gives -2.40001pt on my system. > > -Mark > Le mardi 22 juillet 2008 à 17:17 +0100, Mark Wibrow a écrit : > 2008/7/22 Loïc <xlogo@...>: > > > > > > What interests me is if this computation problem is a bug and if it is > > possible to solve it in a near future. Or is this approximation with > > mathematical expression is part of pgf and pdf features and cannot be > > solved? > > > > In this case, the foreach loop is actually using native TeX > arithmetic. As is pointed out in the manual, TeX is not good with > numbers that are not multiples of 2^-n. This can be seen with a simple > example: > > \newdimen\mydimen > \mydimen=-3.6pt > \advance\mydimen by1.2pt > > Unfortunately there isn't a lot that can be done about it currently, > so the ``long hand'' method is really the only option. > > Sorry > > Mark > ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ pgf-users mailing list pgf-users@... https://lists.sourceforge.net/lists/listinfo/pgf-users
	Re: Computation problems by TeXWorld :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message Loïc a écrit : > Many thanks for your answer. > I explain why it's important for me: > > I have written a PGF/TikZ export for the dynamic geometry software > called GeoGeBra (http://www.geogebra.org) and I'm finalizing it. > > Is it a PGF or a TikZ export ? > As I explain before here on the list: > > http://www.nabble.com/Plotting-Problem-to18545611.html > > The fact that TeX arithmetic isn't very good makes me think that to plot > functions, it's better to use the GnuPlot method than the native plot > command. > > Am I right? > > Loïc > > Yes. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ pgf-users mailing list pgf-users@... https://lists.sourceforge.net/lists/listinfo/pgf-users
	Re: Computation problems by xlogo :: Rate this Message: Reply to Author \| View Threaded \| Show Only this Message Le mercredi 23 juillet 2008 à 01:08 +0200, TeXWorld a écrit : > Loïc a écrit : > > Many thanks for your answer. > > I explain why it's important for me: > > > > I have written a PGF/TikZ export for the dynamic geometry software > > called GeoGeBra (http://www.geogebra.org) and I'm finalizing it. > > > > > Is it a PGF or a TikZ export ? All instruction are inside a "tikzpicture" environment. Loïc ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ pgf-users mailing list pgf-users@... https://lists.sourceforge.net/lists/listinfo/pgf-users