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In this video we’re going to look at using GeoGebra to generate TikZ code to use in our LaTeX documents. GeoGebra is a great tool for creating and displaying mathematical diagrams. You can get a copy of GeoGebra from the GeoGebra website, www.geogebra.org.

Let’s start by creating a simple diagram in GeoGebra. First we’ll add a circle using the ‘Circle with Centre through Point’ tool.

Next we’ll add a polygon inside our circle using the ‘Polygon’ tool.

Then we’ll measure an angle inside this polygon using the angle tool.

Now we’ll add a straight line going through two points on the circle using the ‘Line through Two Points’ tool.

We’ll finish up by turning the grid on. To do this we select the ‘Move’ tool, right click on the background and select the ‘Grid’ option.

Now to export this as TikZ code we open the file menu, hover over ‘Export’ and click on ‘Graphics View as PGF/TikZ’.

We then tell GeoGebra how much of the grid we want included in our ‘tikzpicture’ by altering the x and y minimum and maximum points. You’ll see a blue box represent this area on the grid. Next we check the format is set to LaTeX article class and then click the generate button.

Now if we hit ‘Copy to Clipboard’ we can then paste it into an empty tex file. You’ll notice that it has generated a preamble where it loads up the TikZ package and a TikZ library, it sets the page style to ‘empty’ and it also defines a new command:

\usepackage{pgf,tikz}
\usetikzlibrary{arrows}
\pagestyle{empty}
\newcommand{\degre}{\ensuremath{^\circ}}


Then it begins the document and defines some colours before opening a ‘tikzpicture’ environment:

\definecolor{qqwuqq}{rgb}{0,0.39,0}
\definecolor{zzttqq}{rgb}{0.6,0.2,0}
\definecolor{xdxdff}{rgb}{0.49,0.49,1}
\definecolor{qqqqff}{rgb}{0,0,1}
\definecolor{cqcqcq}{rgb}{0.75,0.75,0.75}


If we compile the code we’ll see it appear in the document. As it’s generated from TikZ code rather than an image, it’s very high quality.

We could also turn the TikZ picture into a figure to give us more control over things like positioning. To do this we simply enclose the ‘tikzpicture’ environment in the ‘figure’ environment. We can then add a placement specifier, a caption and a label:

\begin{figure}[!h]

<tikzpicture environment>

\label{circle1}
\caption{TikZ from GeoGebra}
\end{figure}


Now if we want to include this figure in an existing document we can copy over everything in the figure environment. We also need to make sure we copy over the relevant parts of the preamble if they’re not in our existing docs preamble already. Therefore we’ll copy over the \usepackage command and \usetikzlibrary command as well as the \newcommand definition. Finally we also need to copy over the colour definitions.

If we go back to GeoGebra we can alter the way our diagram looks by right clicking on it and changing the object properties. For example we can change colours, point styles, line styles and line thickness.

Another useful thing we can do with GoeGebra is export to Tikz in a beamer format so that we can add diagrams into presentations. To do this we export like before except we select the ‘LaTeX (beamer class)’ option.

If we now copy this into a blank tex file and compile the document you’ll notice it has generated a number of slides which build up the diagram piece by piece:

This is due to the \onslide overlay specifications that GeoGebra has automatically generated for us. For example this \onslide command tells beamer to show the circle from slide four onwards:

\onslide<4->{
\draw [color=ffqqtt] (2,1) circle (2.82cm);
}


We can edit these overlay specifications to make the diagram come together in whatever way we want. For example we may want to make the circle appear on the same slide that point B appears. To do this we change this \onslide command from <4-> to <3-> and then, as the circle was the only item to appear on slide four, we knock the numbering of all overlay specifications above four down by one. Again if you want to add this frame into another beamer presentation you can just copy over all the relevant parts as we did with the document earlier.

This concludes our discussion on using GeoGebra to generate TikZ code. In the next post we’ll look at creating flow charts. Please do keep in touch with us via Facebook, Twitter & Google+.

###Other posts in this series Basic Drawing Using TikZ

Creating Flowcharts with TikZ

Circuit Diagrams Using Circuitikz

Creating Mind Maps Using TikZ

Posted by Josh Cassidy on 28 Aug 2013

In the next few blog posts we’re going to show you some of the interesting things you can do using the TikZ package. The TikZ package is a package that allows you to draw high quality and often quite complex diagrams. In this post we’re going to show you some of the basics and show you how to draw simple shapes and lines.

To get started with TikZ we need to load up the TikZ package:

\usepackage{tikz}


Now whenever we want to create a TikZ diagram we need to use the ‘tikzpicture’ environment.

\begin{tikzpicture}

<code goes here>

\end{tikzpicture}


## Basic Shapes

One of the simplest and most commonly used commands in TikZ is the \draw command. To draw a straight line we use this command, then we enter a starting co-ordinate, followed by two dashes before the ending co-ordinate. We then finish the statement by closing it with a semicolon.

\draw (0,0) -- (4,0);


We can then add more co-ordinates in like this to make it a square:

\draw (0,0) -- (4,0) -- (4,4) -- (0,4) -- (0,0);


However this isn’t particularly good style. As we are drawing a line that ends up in the same place we started, it is better to finish the statement with the keyword ‘cycle’ rather than the last co-ordinate.

\draw (0,0) -- (4,0) -- (4,4) -- (0,4) -- cycle;


To simplify this code further we can use the ‘rectangle’ keyword after the starting co-ordinate and then follow it with the co-ordinate of the corner diagonally opposite.

\draw (0,0) rectangle (4,4);


We can also add lines that aren’t straight. For example, this is how we draw a parabola:

\draw (0,0) parabola (4,4);


To add a curved line we use ‘control points’. We begin with our starting co-ordinate, then use two dots followed by the keyword ‘controls’ and then the co-ordinates of our control points separated by an ‘and’. Then after two more dots we have the final point. These control points act like magnets attracting the line in their direction.

\draw (0,0) .. controls (0,4) and (4,0) .. (4,4);


We can then add a circle like this. The first co-ordinate is the circle’s centre and the length in brackets at the end is the circle’s radius.

\draw (2,2) circle (3cm);


This is how we draw an ellipse. This time the lengths in the brackets separated by an ‘and’, are the x-direction radius and the y-direction radius respectively.

\draw (2,2) ellipse (3cm and 1cm);


This is how we draw an arc. In the final bracket we enter the starting angle, the ending angle and the radius. This time they are separated by colons.

\draw (3,0) arc (0:75:3cm);


To customise the way these lines are drawn we add extra arguments into the \draw command. For example we can edit the circle we drew so that the line is red, thick and dashed.

\draw[red,thick,dashed] (2,2) circle (3cm);


##Grids Very often when drawing diagrams we will want to draw a grid. To do this we use the \draw command followed by by some additional arguments. For example we specify the grid step size using step= and a length. We’ve also specified the colour ‘gray’ and told it to make the lines ‘very thin’. After these arguments we enter the co-ordinates of the bottom left corner, followed by the keyword ‘grid’ and then the co-ordinates of the top right corner.

\draw[step=1cm,gray,very thin] (-2,-2) grid (6,6);


If we want to remove the outer lines around this grid we can crop the size slightly like this.

\draw[step=1cm,gray,very thin] (-1.9,-1.9) grid (5.9,5.9);


##Colour Filling Now lets add a shape onto our grid and colour it in. To do this we use the \fill command instead of the \draw command. Then in square brackets we enter a colour. For example this specifies a colour that is 40% blue mixed with 60% white. Then we just specify a closed shape as we would normally.

\fill[blue!40!white] (0,0) rectangle (4,4);


If we wanted to add a border around this shape we could change it to the \filldraw command and then alter the arguments so that we have both a fill colour and a draw colour specified.

\filldraw[fill=blue!40!white, draw=black] (0,0) rectangle (4,4);


If instead of one solid colour we want a colour gradient, we could change it to the \shade command. Then in the square brackets we specify a left colour and a right colour.

\shade[left color=blue,right color=red] (0,0) rectangle (4,4);


Instead of doing it from left to right we could do it from top to bottom.

\shade[top color=blue,bottom color=red] (0,0) rectangle (4,4);


Or we could even change it by specifying an inner and outer colour like this.

\shade[inner color=blue,outer color=red] (0,0) rectangle (4,4);


Finally we could also add a border to this by using the \shadedraw command and adding a draw colour.

\shadedraw[inner color=blue,outer color=red, draw=black] (0,0) rectangle (4,4);


##Axes Let’s finish this post by adding some labeled axes to our grid. To do this we draw two normal lines both from (0,0), but we’ll make them thick and add arrowheads using a dash and a pointed bracket.

\draw[thick,->] (0,0) -- (4.5,0);
\draw[thick,->] (0,0) -- (0,4.5);


We can also label our axes using nodes. To do this we add the keyword ‘node’ into both draw statements next to the end co-ordinates, followed by an anchor specification in square brackets and the text in curly brackets. Every node we create in TikZ has a number of anchors. So when we specify the north west anchor for the x-axis node, we are telling TikZ to use the anchor in the top left hand corner to anchor the node to the co-ordinate.

\draw[thick,->] (0,0) -- (4.5,0) node[anchor=north west] {x axis};
\draw[thick,->] (0,0) -- (0,4.5) node[anchor=south east] {y axis};


To finish our axes we can add in ticks and numbering like this:

\foreach \x in {0,1,2,3,4}
\draw (\x cm,1pt) -- (\x cm,-1pt) node[anchor=north] {$\x$};
\foreach \y in {0,1,2,3,4}
\draw (1pt,\y cm) -- (-1pt,\y cm) node[anchor=east] {$\y$};


This clever piece of code uses two ‘for each’ loops to systematically go along the axes adding the ticks and numbers. In each one, the variable x or y takes on all of the numbers in the curly brackets, each in turn and executes the \draw command.

This concludes our discussion on basic drawing in TikZ. If you want to play around with the document we created in this post you can access it here. In the next post we’ll look exporting TikZ code from GeoGebra. Please do keep in touch with us via Facebook, Twitter & Google+.

###Other posts in this series Generating TikZ Code from GeoGebra

Creating Flowcharts with TikZ

Circuit Diagrams Using Circuitikz

Creating Mind Maps Using TikZ

Posted by Josh Cassidy on 27 Aug 2013

In the last post we looked at animating our slides using overlay specifications. In this post we’re going to look at editing the way our presentation looks using themes. We’ll also look at printing handouts.

##Presentation Themes In the first video we set up our presentation with the ‘Boadilla’ theme like this:

\usetheme{Boadilla}


There are lots of different predefined presentation themes available for us to use. Here are a few of them. This is the ‘Bergen’ theme:

There are also themes that include navigation bars, for example the ‘Antibes’ theme:

We could also use a theme that includes a table of contents sidebar, like the ‘Hannover’ theme:

The ‘Singapore’ theme is one that includes what beamer calls a ‘Mini Frame Navigation’:

Finally there are also themes like ‘Warsaw’ that have the section and subsection titles at the top of each frame:

##Colour, Font, Inner & Outer Themes The presentation themes control everything about how the presentation looks. However beamer gives us more flexibility by allowing us to change the colour theme, font theme, inner theme and outer theme, all separately. This is really handy as it means if we like a theme like ‘Warsaw’ but, for example, want to change the colour theme, then we can load the ‘Warsaw’ presentation theme and then override the colour theme with one of beamer’s predefined colour themes. We change the colour scheme using the \usecolortheme command followed by the colour theme in curly brackets. Note that these themes are different to the presentation themes we used earlier. For example, the ‘crane’ colour theme:

The inner theme dictates the style of the title and part pages, the itemize, enumerate, description, block, theorem and proof environments as well as figures, tables, footnotes and bibliography entries. For example we could also load up the ‘rectangles’ inner theme. We do this using the \useinnertheme command. This has made our table of contents and lists use rectangles as bullet points:

The outer theme dictates the style of the head and footline, the logo, the sidebars and the frame title. We can specify this theme using the \useinnertheme command. As we’re using ‘Warsaw’, by default we are using the ‘shadow’ outer theme, but we could change this to the ‘tree’ theme if we wanted to change the top navigation bar to a tree like structure:

Finally, I could also change the font theme using the \usefonttheme command and a predefined font theme like the ‘serif’ theme.

All the information about the different themes available can be found in the documentation.

##Handouts Now let’s briefly look at creating handouts for our presentation. To do this we add the keyword ‘handout’ into square brackets in the document class command. We then use the ‘pgfpages’ package to help us print multiple slides on a page. After loading the package we use the \pgfpagesuselayout command. In the curly brackets we specify how many frames we want on a sheet. In the square brackets we specify the paper size and how much border shrink we want:

\documentclass[handout]{beamer}
\usepackage{pgfpages}
\pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm]


If we wanted to put four frames on a sheet we could simply change the 2 to a 4 and then add the ‘landscape’ keyword into the square brackets.

\pgfpagesuselayout{4 on 1}[a4paper,border shrink=5mm,landscape]


This concludes our discussion on themes and handouts and also our series on creating presentations with beamer. If you want to play around with the presentation we created in this series you can access it here. Do have a look at the video series we produced alongside these blog posts here. Please do keep in touch with us via Facebook, Twitter & Google+.

###Other posts in this series:

pt 1 - Getting Started

pt 2 - Lists, Columns, Pictures, Descriptions & Tables

pt 3 - Blocks, Code, Hyperlinks & Buttons

pt 4 - Overlay Specifications

Posted by Josh Cassidy on 22 Aug 2013

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