Recent changes to patches

#26 [trig operations] Better sin/cos operation

Stefan Pinnow — Mon, 31 Dec 2018 10:49:49 -0000

status: open --> closed-accepted

[trig operations] Better sin/cos operation

Stefan Pinnow — Thu, 21 Jun 2018 16:59:29 -0000

In bug #482 it was suggested to improve the parabola operation by changing the given coordinates, which were found by "trial and error" as it was stated in the source code.

As it seems also the coordinates for the sin and cos operation are found by trial and error. But even though there is no analytical solution, maybe these coordinates should be replaced by something more "mathematical".

In my comment below the bug report #482 I already tested if the bezierplot could give a better result, which it does not. Also Kpym made a suggestion for an improvement, but it also seems to be worse than the current implementation.

Via email I received a "real" mathematical approach for an improvement by Linus, the author of the bezierplot package. He wrote two python scripts (the attachments) to search for an optimal solution. Both of them found the same solution (given in the last line of the scripts). These indeed seem to be better than the current implementation. Here the "proof":

% used PGFPlots v1.16
\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
    \pgfplotsset{
        compat=1.16,
        every axis/.append style={
            no markers,
            samples=101,
        },
    }
\makeatletter
\def\pgfpathsine#1{%
  {%
    \pgf@process{#1}% untransformed
    \pgf@xc=\pgf@x%
    \pgf@yc=\pgf@y%
    \pgf@pt@x=\pgf@path@lastx% evil trickery to transform to the last point
    \pgf@pt@y=\pgf@path@lasty%
    \pgfpathcurveto%
% -----------------------------------------------------------------------------
%     % old solution
      {\pgfqpoint{.31831\pgf@xc}{.5\pgf@yc}}% found by trial and error
      {\pgfqpoint{.63503\pgf@xc}{\pgf@yc}}% found by trial and error
% -----------------------------------------------------------------------------
%      % new solution from Linus' python script (package author of `bezierplot')
%      {\pgfqpoint{.3260\pgf@xc}{.5120\pgf@yc}}%
%      {\pgfqpoint{.6380\pgf@xc}{\pgf@yc}}%
% -----------------------------------------------------------------------------
      {\pgfqpoint{\pgf@xc}{\pgf@yc}}%
  }%
}

\def\pgfpathcosine#1{%
  {%
    \pgf@process{#1}% untransformed
    \pgf@xc=\pgf@x%
    \pgf@yc=\pgf@y%
    \pgf@pt@x=\pgf@path@lastx% evil trickery to transform to the last point
    \pgf@pt@y=\pgf@path@lasty%
    \pgfpathcurveto%
% -----------------------------------------------------------------------------
%     % old solution
      {\pgfqpoint{.36497\pgf@xc}{0pt}}%         found by trial and error
      {\pgfqpoint{.68169\pgf@xc}{.5\pgf@yc}}%   found by trial and error
% -----------------------------------------------------------------------------
%      % new solution from Linus' python script (package author of `bezierplot')
%      {\pgfqpoint{.3620\pgf@xc}{0pt}}%
%      {\pgfqpoint{.6740\pgf@xc}{.4880\pgf@yc}}%
% -----------------------------------------------------------------------------
      {\pgfqpoint{\pgf@xc}{\pgf@yc}}%
  }%
}
\makeatother
\begin{document}
\begin{tikzpicture}
    \begin{axis}
        % real solution
        \addplot+ [domain=0:pi/2] {sin(deg(x))};

        % tikz function call (current implementation)
        \draw [red,opacity=0.5,dashed]
            (0,0) sin (pi/2,1);
        % corresponds to the old implementation
        \draw [red!50,opacity=0.5,loosely dashed,xscale=pi/2]
            (0,0) .. controls (0.31831,0.5) and (0.63503,1) .. (1,1);

%        % corresponds to the new implementation suggested by Kpym
%        \draw [green!50!black,opacity=0.5,densely dotted,xscale=pi/2]
%            (0,0) .. controls (1/pi,0.5) and (2/pi,1) .. (1,1);
        % corresponds to the new implementation from Linus' python script
        \draw [green!50,opacity=0.5,densely dotted,xscale=pi/2]
            (0,0) .. controls (0.3260,0.5120) and (0.6380,1) .. (1,1);
    \end{axis}
\end{tikzpicture}
\begin{tikzpicture}
    \begin{axis}
        % real solution
        \addplot+ [domain=0:pi/2] {cos(deg(x))};

        % tikz function call (current implementation)
        \draw [red,opacity=0.5,dashed]
            (0,1) cos (pi/2,0);
        % corresponds to the old implementation
        \draw [red!50,opacity=0.5,loosely dashed,xscale=pi/2]
            (0,1) .. controls (0.36497,1) and (0.68169,0.5) .. (1,0);

%        % corresponds to the new implementation suggested by Kpym
%        % (the y values of the control variables have to be `1-<value>')
%        \draw [green!50!black,opacity=0.5,densely dotted,xscale=pi/2]
%            (0,1) .. controls (1-2/pi,1) and (1-1/pi,0.5) .. (1,0);
        % corresponds to the new implementation from Linus' python script
        % (the y values of the control variables have to be `1-<value>')
        \draw [green!50,opacity=0.5,densely dotted,xscale=pi/2]
            (0,1) .. controls (0.3620,1) and (0.6740,0.5120) .. (1,0);
    \end{axis}
\end{tikzpicture}
\end{document}

[trig operations] Better sin/cos operation

Stefan Pinnow — Thu, 21 Jun 2018 16:59:29 -0000

Ticket 26 has been modified: [trig operations] Better sin/cos operation
Edited By: Stefan Pinnow (mo-gul)
Status updated: u'open' => u'closed-accepted'

#21 Leaking space in \pgfgettransform

Stefan Pinnow — Thu, 21 Jun 2018 04:37:28 -0000

Description has changed:

Diff:

--- old
+++ new
@@ -1 +1 @@
-Macro \pgfgettransform in file pgfcoretransformations.code.tex is leaking a space.
+Macro `\pgfgettransform` in file `pgfcoretransformations.code.tex` is leaking a space.

status: open --> closed-accepted

#24 Typos in PGF manual

Stefan Pinnow — Thu, 21 Jun 2018 04:24:49 -0000

status: open --> closed-accepted

#25 Correct bug that prevents "/tikz/data visualization/also at" from being assigned a list.

Stefan Pinnow — Mon, 28 May 2018 19:39:17 -0000

status: open --> closed-accepted

#25 Correct bug that prevents "/tikz/data visualization/also at" from being assigned a list.

Stefan Pinnow — Sun, 27 May 2018 17:56:24 -0000

Description has changed:

Diff:

--- old
+++ new
@@ -1,5 +1,5 @@
 Hello,
-I believe the MWE below shows a contradiction between the PGF manual and the behaviour of the `also at` key for grids in datavisualizations, viz that this key may be assigned a list in the same way as the t`at` key. The proposed patch makes the MWE compile, is it the right way to do it ?
+I believe the MWE below shows a contradiction between the PGF manual and the behaviour of the `also at` key for grids in datavisualizations, viz that this key may be assigned a list in the same way as the `at` key. The proposed patch makes the MWE compile, is it the right way to do it ?
 cheers,
 Adrian

#25 Correct bug that prevents "/tikz/data visualization/also at" from being assigned a list.

Stefan Pinnow — Sun, 27 May 2018 17:35:26 -0000

labels: --> data visualization
Description has changed:

Diff:

--- old
+++ new
@@ -1,19 +1,20 @@
 Hello,
-I believe the MWE below shows a contradiction between the PGF manual and the behaviour of the "also at" key for grids in datavisualizations, viz that this key may be assigned a list in the same way as the "at" key. The proposed patch makes the MWE compile, is it the right way to do it ?
+I believe the MWE below shows a contradiction between the PGF manual and the behaviour of the `also at` key for grids in datavisualizations, viz that this key may be assigned a list in the same way as the t`at` key. The proposed patch makes the MWE compile, is it the right way to do it ?
 cheers,
 Adrian

 The following MWE contains three graphs. The first is copied from the
-pgfmanual 3.0.1a page 798. The third merely replaces "at" by "also at",
-which should be allowed according to the manual p799 ("also at" can be
-fed a list just as "at"), but compilation fails on this third graph with
+pgfmanual 3.0.1a page 798. The third merely replacest `at` by `also at`,
+which should be allowed according to the manual p799 (`also at` can be
+fed a list just as `at`), but compilation fails on this third graph with
 a

-Package PGF Math Error: Could not parse input '1, 1.5,
-2' as a floating point number, sorry. The unreadable part was near the
-decimal separator ', 1.5, 2'. Do you need the option 'read comma as
-period'?
+> Package PGF Math Error: Could not parse input '1, 1.5,
+> 2' as a floating point number, sorry. The unreadable part was near the
+> decimal separator ', 1.5, 2'. Do you need the option 'read comma as
+> period'?

+~~~
 \documentclass{scrartcl}
 \usepackage{tikz}
 \usetikzlibrary{datavisualization}
@@ -46,3 +47,4 @@
 };

 \end{document}
+~~~

Correct bug that prevents "/tikz/data visualization/also at" from being assigned a list.

Adrian Daerr — Sun, 15 Oct 2017 21:20:36 -0000

Hello,
I believe the MWE below shows a contradiction between the PGF manual and the behaviour of the "also at" key for grids in datavisualizations, viz that this key may be assigned a list in the same way as the "at" key. The proposed patch makes the MWE compile, is it the right way to do it ?
cheers,
Adrian

The following MWE contains three graphs. The first is copied from the
pgfmanual 3.0.1a page 798. The third merely replaces "at" by "also at",
which should be allowed according to the manual p799 ("also at" can be
fed a list just as "at"), but compilation fails on this third graph with
a

Package PGF Math Error: Could not parse input '1, 1.5,
2' as a floating point number, sorry. The unreadable part was near the
decimal separator ', 1.5, 2'. Do you need the option 'read comma as
period'?

\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{datavisualization}
\usetikzlibrary{datavisualization.formats.functions}

\begin{document}

\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={grid={minor={at={1, 1.5, 2}}}}]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};

\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={grid={minor={also at={1}, also at={1.5}, also at={2}}}}]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};

\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={grid={minor={also at={1, 1.5, 2}}}}]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};

\end{document}

Correct bug that prevents "/tikz/data visualization/also at" from being assigned a list.

Adrian Daerr — Sun, 15 Oct 2017 21:20:36 -0000

Ticket 25 has been modified: Correct bug that prevents "/tikz/data visualization/also at" from being assigned a list.
Edited By: Stefan Pinnow (mo-gul)
Description updated:
--- description-old

+++ description-new

@@ -1,19 +1,20 @@

Hello,
-I believe the MWE below shows a contradiction between the PGF manual and the behaviour of the "also at" key for grids in datavisualizations, viz that this key may be assigned a list in the same way as the "at" key. The proposed patch makes the MWE compile, is it the right way to do it ?
+I believe the MWE below shows a contradiction between the PGF manual and the behaviour of the also at key for grids in datavisualizations, viz that this key may be assigned a list in the same way as the tat key. The proposed patch makes the MWE compile, is it the right way to do it ?
cheers,
Adrian

The following MWE contains three graphs. The first is copied from the
-pgfmanual 3.0.1a page 798. The third merely replaces "at" by "also at",
-which should be allowed according to the manual p799 ("also at" can be
-fed a list just as "at"), but compilation fails on this third graph with
+pgfmanual 3.0.1a page 798. The third merely replacest at by also at,
+which should be allowed according to the manual p799 (also at can be
+fed a list just as at), but compilation fails on this third graph with
a

-Package PGF Math Error: Could not parse input '1, 1.5,
-2' as a floating point number, sorry. The unreadable part was near the
-decimal separator ', 1.5, 2'. Do you need the option 'read comma as
-period'?
+> Package PGF Math Error: Could not parse input '1, 1.5,
+> 2' as a floating point number, sorry. The unreadable part was near the
+> decimal separator ', 1.5, 2'. Do you need the option 'read comma as
+> period'?

+~~~
\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{datavisualization}
@@ -46,4 +47,5 @@

};

\end{document}
+~~~