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Tips and tricks: Difference between revisions
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=Tiny helper functions= | ==Tiny helper functions== | ||
This is a list of tiny helper functions (the equivalent of e.g., shell aliases), the kind one would have on its {{Path|.octaverc}} file. | This is a list of tiny helper functions (the equivalent of e.g., shell aliases), the kind one would have on its {{Path|.octaverc}} file. | ||
== replace help with man == | === replace help with man === | ||
If you use octave too much, you'll find yourself trying to use {{Codeline|help}} instead of {{Codeline|man}} on bash. This function will fix that so you can use {{Codeline|man}} in your octave instance (you can also do the opposite, create a {{Codeline|help}} alias in bash but {{Codeline|man}} has less characters). | If you use octave too much, you'll find yourself trying to use {{Codeline|help}} instead of {{Codeline|man}} on bash. This function will fix that so you can use {{Codeline|man}} in your octave instance (you can also do the opposite, create a {{Codeline|help}} alias in bash but {{Codeline|man}} has less characters). | ||
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endfunction</pre>}} | endfunction</pre>}} | ||
=C++= | ==C++== | ||
=== Real matrix operations=== | |||
This is a table of matrix operations commonly performed in Octave and their equivalents in C++ when using the octave libraries. | This is a table of matrix operations commonly performed in Octave and their equivalents in C++ when using the octave libraries. | ||
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* The names of Octave internal functions, such as mx_el_gt, are not documented and are subject to change. Functions such as mx_el_gt may eventually be available at both the scripting level and in C++ under more common names such as gt. | * The names of Octave internal functions, such as mx_el_gt, are not documented and are subject to change. Functions such as mx_el_gt may eventually be available at both the scripting level and in C++ under more common names such as gt. | ||
==Complex Matrix Operations== | ===Complex Matrix Operations=== | ||
<table> | <table> | ||
<tr><td><b>Operation</b></td><td><b>Octave</b></td><td><b>C++</b></td></tr> | <tr><td><b>Operation</b></td><td><b>Octave</b></td><td><b>C++</b></td></tr> | ||
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</table> | </table> | ||
==General== | |||
= | ===A funny formatting trick with fprintf found by chance=== | ||
==A funny formatting trick with fprintf found by chance== | |||
Imagine that you want to create a text table with fprintf with 2 columns of 15 characters width and both right justified. How to do this thing? | Imagine that you want to create a text table with fprintf with 2 columns of 15 characters width and both right justified. How to do this thing? | ||
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Hello | World | Hello | World | ||
==Load Comma Separated Values (*.csv) files== | ===Load Comma Separated Values (*.csv) files=== | ||
A=textread("file.csv", "%d", "delimiter", ","); | A=textread("file.csv", "%d", "delimiter", ","); | ||
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The next version of octave (3.6) implements the <code>CollectOutput</code> switch as seen in example 8 here: http://www.mathworks.com/help/techdoc/ref/textscan.html | The next version of octave (3.6) implements the <code>CollectOutput</code> switch as seen in example 8 here: http://www.mathworks.com/help/techdoc/ref/textscan.html | ||
==Using Variable Strings in Octave Commands== | ===Using Variable Strings in Octave Commands=== | ||
For example, to plot data using a string variable as a legend: | For example, to plot data using a string variable as a legend: | ||
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These same tricks are useful for reading and writing data files with unique names, etc. | These same tricks are useful for reading and writing data files with unique names, etc. | ||
==Vectorizing Tricks== | ===Vectorizing Tricks=== | ||
You can easily fill a vector with an index: | You can easily fill a vector with an index: | ||
for i=1:n, x(i) = i; end | for i=1:n, x(i) = i; end | ||
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This works for expressions on the index by wrapping the index in an expression: | This works for expressions on the index by wrapping the index in an expression: | ||
for i=1:n, x(i) = sin(2*pi*i*f/r); end | for i=1:n, x(i) = sin(2*pi*i*f/r); end | ||
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You can also work with other vectors this way: | You can also work with other vectors this way: | ||
for i=1:n, x(i) = sin(2*pi*y(i)*f/r); end | for i=1:n, x(i) = sin(2*pi*y(i)*f/r); end | ||
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*tricks relying on fortran indexing | *tricks relying on fortran indexing | ||
===Other references=== | ====Other references==== | ||
*MATLAB array manipulation tips and tricks by Peter Acklam: http://home.online.no/~pjacklam/matlab/doc/mtt/index.html | *MATLAB array manipulation tips and tricks by Peter Acklam: http://home.online.no/~pjacklam/matlab/doc/mtt/index.html | ||
*The MathWorks: Code Vectorization Guide: http://www.mathworks.com/support/tech-notes/1100/1109.html | *The MathWorks: Code Vectorization Guide: http://www.mathworks.com/support/tech-notes/1100/1109.html | ||