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Add warning about floating-point arithmetic to foreach introduction #1053

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7f7db96
manual: add warning about floating-point arithmetic #1050
3geek14 Sep 20, 2021
6e0700b
Update doc/generic/pgf/text-en/pgfmanual-en-tutorial.tex
3geek14 Sep 25, 2021
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12 changes: 9 additions & 3 deletions doc/generic/pgf/text-en/pgfmanual-en-tutorial.tex
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Expand Up @@ -1100,11 +1100,17 @@ \subsection{Repeating Things: For-Loops}
\end{codeexample}

If you provide \emph{two} numbers before the |...|, the |\foreach| statement
will use their difference for the stepping:
will use their difference for the stepping, but be wary of floating-point
rounding errors:
%
\begin{codeexample}[]
\tikz \foreach \x in {-1,-0.5,...,1}
\draw (\x cm,-1pt) -- (\x cm,1pt);
\begin{tikzpicture}
\foreach \x in {-1,-0.5,...,1}
\draw (\x cm,-1pt) -- (\x cm,1pt);
\foreach \x in {-1,-0.9,...,0}
% tick at 0 is not drawn due to rounding errors
\draw (\x cm,-7pt) -- (\x cm,-5pt);
\end{tikzpicture}
\end{codeexample}

We can also nest loops to create interesting effects:
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