# HG changeset patch # User Kai T. Ohlhus # Date 1476194544 -7200 # Node ID e2fce1335771516dfd9addeb311c1d26896c5734 # Parent 6a5226561c9ba47a54ccf8aca0b51e8d3cb845d4 Remove examples page, there is already one at wiki.octave.org. diff -r 6a5226561c9b -r e2fce1335771 examples.md --- a/examples.md Tue Oct 11 16:02:00 2016 +0200 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,231 +0,0 @@ ---- -layout: default -title: Examples -menu: true ---- - -## Using Octave - -First, follow the [installation guide](install.html) to install Octave on your system. Then, launch the interactive prompt by typing `octave` in a terminal or by clicking the icon in the programs menu. For further guidance, see the manual page on [Running Octave]({{site.docs_url}}Running-Octave.html). - - -## Language Basics - -Click the headings below to see a manual page related to each topic -{: .panel} - - -### [Variable Assignment]({{site.docs_url}}Variables.html) - -Assign values to variables with `=` (Note: assignment is pass-by-value) - - -### [Comments]({{site.docs_url}}Comments.html) - -`%` starts a comment block that continues to the end of the line. - - -### [Evaluation]({{site.docs_url}}Simple-Examples.html) - -The output of every command is printed to the console unless terminated with `;`. -The `disp()` command can be used to print output anywhere. Use `exit` to quit the console. - -{% highlight matlab %} -t = 99 + 1 % prints 't = 100' -t = 99 + 1; % nothing is printed -disp(t); - 100 -{% endhighlight %} - - -### [Math]({{site.docs_url}}Arithmetic.html) - -Many mathematical operators are available in addition to the standard arithmetic. -Operations are floating-point. -{% highlight matlab %} -x = 3/4*pi; -y = sin(x) - 0.70711 -{% endhighlight %} - - -### [Matrices]({{site.docs_url}}Matrices.html) - -Arrays in Octave are called matrices. -One-dimensional matrices are referred to as vectors. -Use `space` or `,` to separate elements and `;` to start a new row. - -{% highlight matlab %} -rowVec = [8 6 4] - 8 6 4 -columnVec = [8; 6; 4] - 8 - 6 - 4 -mat = [8 6 4; 2 0 -2] - 8 6 4 - 2 0 -2 -size(mat) - 2 3 -length(rowVec) - 3 -{% endhighlight %} - - -### [Linear Algebra]({{site.docs_url}}Linear-Algebra.html) - -Many common linear algebra operations are simple to program using Octave's matrix syntax. - -{% highlight matlab %} -columnVec * rowVec - 64 48 32 - 48 36 24 - 32 24 16 -rowVec * columnVec - 116 -columnVec' - 8 6 4 -{% endhighlight %} - - -### [Accessing Elements]({{site.docs_url}}Index-Expressions.html) - -Octave is 1-indexed. Matrix elements are accessed as `matrix(rowNum, columnNum)`. - -{% highlight matlab %} -mat(2,3) - -2 -{% endhighlight %} - - -### [Iteration]({{site.docs_url}}Statements.html) - -Octave supports `for` and `while` loops, as well as other control flow structures. - -{% highlight matlab %} -x = zeros(50,1); -for i=1:2:100 % iterate from 1 to 100 with step size 2 - x(i) = i^2; -end - -y = zeros(50,1); -k = 1; -step = 2; -while k<=(100-step) - y(i) = k^2; - k = k + step; -end -{% endhighlight %} - - -### [Vectorization]({{site.docs_url}}Vectorization-and-Faster-Code-Execution.html) - -For-loops can often be replaced or simplified using vector syntax. -The operators `*`,`/`,`^`,`%` all support element-wise operations using `.`. -Many other functions operate element-wise by default (`sin`,`+`,`-`, etc.). - -{% highlight matlab %} -i = 1:2:100; % create a 50-element array -x = i.^2; % each element is squared -y = x + 9; % add 9 to each element -z = y./i; % divide each element in y by the corresponding value in i -w = sin(i/10); % take the sine of each element ÷ 10 -{% endhighlight %} - - -### [Plotting]({{site.docs_url}}Two_002dDimensional-Plots.html) - -`plot` can be called with vector arguments to create 2D line and scatter plots. - -{% highlight matlab %} -plot(w,i/10); -title('w = sin(i/10)'; -xlabel('i ÷ 10'); -ylabel('w'); -{% endhighlight %} - - sine plot

- - -### [Strings]({{site.docs_url}}Strings.html) - -Strings are simply arrays of characters. -Strings can be composed using `printf`-style formatting with `sprintf` and `fprintf`. -{% highlight matlab %} -firstString = 'hello world'; -secondString = '!'; -[firstString,secondString] - hello world! -fprintf('%s %.10f \n', 'The number is:', 10) - The number is: 10.0000000000 -{% endhighlight %} - - -### [If-else]({{site.docs_url}}The-if-Statement.html) - -Conditional statements can be used to create branching logic in your code. - -{% highlight matlab %} -% Print 'Foo' if divisible by 7, -% 'Fizz' if divisible by 3, -% 'Buzz' if divisible by 5, -% 'FizzBuzz' if divisible by 3 and 5 -for (i = 1:1:100) - outputString = ''; - if (rem(i,3) == 0) % rem is the remainder function - outputString = [outputString, 'Fizz']; - end - if (rem(i,5) == 0) - outputString = [outputString, 'Buzz']; - elseif (rem(i,7) == 0) - outputString = 'Foo'; - else - outputString = outputString; - end - fprintf('i=%g: %s \n',i,outputString); -end -{% endhighlight %} - -{% highlight text %} - ... - i=12: Fizz - i=13: - i=14: Foo - i=15: FizzBuzz - ... -{% endhighlight %} - - -### [Help]({{site.docs_url}}Simple-Examples.html#Help-and-Documentation) - -The `help` and `doc` commands can be invoked at the Octave prompt to print documentation for any function. - -{% highlight matlab %} -help plot -doc plot -{% endhighlight %} - - -### [Packages]({{site.docs_url}}Packages.html) - -Community-developed packages can be added from the -[Octave Forge](http://octave.sourceforge.net/index.html) -to extend the functionality of Octave's core library. -(Matlab users: Forge packages act similarly to Matlab's toolboxes.) -The `pkg` command is used to manage these packages. -For example, to use the image processing library from the Forge, use: - -{% highlight matlab %} -pkg install -forge image % install package -pkg load image % load new functions into workspace -{% endhighlight %} - -