# Tikz, coordinate by trig functions

quick question:

\begin{tikzpicture}
\draw  (0,0) grid (4,2);
\fill[red] (canvas cs:x=1cm,y={sin(120)}) circle (2pt);
\fill[green] (canvas cs:x=2cm,y={sin(45)}) circle (2pt);
\fill[blue] (canvas cs:x=3cm,y=-{sin(30)}) circle (2pt);
\fill[black] (canvas cs:x=4cm,y=5mm+{sin(30)}) circle (2pt); << it does not work
\end{tikzpicture}


How do I insert a trig function within a coordinate calculation, as above last line?

• The nodes are exactly where they are supposed to be. e.g. sin(30) is 0.5, which would be 0.5cm, adding 5mm yields 1cm and that's where the black node is placed. – clocktown May 28 '17 at 9:04
• @clocktown Forget my edit. How do I make tiles 1cmx1cm? – mario May 28 '17 at 10:29

\fill[black] (canvas cs:x=4cm,y={5mm+sin(30)}) circle (2pt);


You basically just have to move that one { to the left a bit. TikZ Syntax can be quite tricky sometimes.

Edit:
The result of these sinus-calculations for y seem to be in a weird unit, at least not a metric one it seems. I always thought cm would be default, but that assumption seems to be wrong here. I'm guessing it's something like pt here. Thus I'd suggest:

\begin{tikzpicture}
\draw  (0,0) grid (4,2);
\fill[red] (canvas cs:x=1cm,y={1cm*sin(120)}) circle (2pt);
\fill[green] (canvas cs:x=2cm,y={1cm*sin(45)}) circle (2pt);
\fill[blue] (canvas cs:x=3cm,y=-{1cm*sin(30)}) circle (2pt);
\fill[black] (canvas cs:x=4cm,y={5mm+1cm*sin(30)}) circle (2pt);
\end{tikzpicture}


1cm* converts it into cm, so you can change it to whatever unit you want.

• @ clocktown Thks, look at it tomorrow. – mario May 25 '17 at 17:13
• @ clocktown See new image, it seems that 1cm*sin(120) returns 1cm plus sin(120). Is that intended? – mario May 28 '17 at 8:52
• It's most likely not a weird unit, but points (1 pt = 1/72.27 in). It appears that if no unit is given, then points are used, try for example \fill[red] (canvas cs:x=1cm,y=28.45) circle (2pt); \fill[green] (canvas cs:x=2cm,y=1cm) circle (2pt); (28.45pt is about 1cm) Also, read the description of the xyz coordinate system in the manual, especially the last two paragraphs, starting with Note and Note furthermore. – Torbjørn T. May 28 '17 at 9:45
• That's what I assumed too. Points is a weird unit to me, anything non metric is for me ;) – clocktown May 28 '17 at 10:00

Package calculator seems to make things easier:

\documentclass[convert={density=300,size=1080x800,outext=.png}]{standalone}

\usepackage{tikz}
\usepackage{calculator}
\usetikzlibrary{rulercompass}
\usetikzlibrary{intersections,quotes,angles}
\usetikzlibrary{calc}

\begin{document}
\begin{tikzpicture}
\draw[step=1cm,black!25,thin] (-1,-1) grid (5,2);
%sin(120)=0.86
\DEGREESSIN{120}{\sol}
\TRUNCATE[2]{\sol}{\sol}
\fill[red] (canvas cs:x=0cm,y={1cm*sin(120)}) circle (2pt)
node[label={[xshift=0.35cm]{\sol}}] {};

\fill[red] (canvas cs:x=0.2cm,y={1cm*\sol}) circle (2pt)
node[label={[xshift=0.35cm, yshift=-0.65cm]{\sol}}] {};

\fill[red] (canvas cs:x=.4cm,y=0.86cm) circle (2pt);
%sin(90)=1
\DEGREESSIN{90}{\sol}
%\TRUNCATE[2]{\sol}{\sol}
\fill[purple] (canvas cs:x=1cm,y={1cm*sin(90)}) circle (2pt)
node[label={[xshift=0.35cm]{\sol}}] {};

\fill[purple] (canvas cs:x=1.2cm,y={1cm*\sol}) circle (2pt)
node[label={[xshift=0.35cm, yshift=-0.65cm]{\sol}}] {};

%sin(45)=0.7
\DEGREESSIN{45}{\sol}
\TRUNCATE[2]{\sol}{\sol}
\fill[green] (canvas cs:x=2cm,y={1*sin(45)}) circle (2pt)
node[label={[xshift=0.35cm]{\sol}}] {};

% sin(30) = 0.5
\DEGREESSIN{30}{\sol}
\TRUNCATE[2]{\sol}{\sol}
\fill[blue] (canvas cs:x=3cm,y={1cm*sin(30)}) circle (2pt)
node[label={[xshift=-0.35cm, yshift=-0.65cm]{\sol}}] {};

\fill[black] (canvas cs:x=3cm,y={5mm+1*sin(30)}) circle (2pt)
node[label={[xshift=0.35cm]{\sol}}] {};

\fill[pink] (canvas cs:x=4cm,y={5mm+1*\sol}) circle (2pt)
node[label={[xshift=0.35cm]{\sol}}] {};
\end{tikzpicture}
\end{document}