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March 15, 2009, 15:58 
Guide: Writing Equations in LaTeX on the CFD Online Forums

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Peter Jones
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This is a brief introduction about how to write equations in the CFD Online discussion forums. The equation functionality is based on LaTeX, a versatile mathematical typesetting system which is often used to write scientific papers and books. With LaTeX mathematical equations are written using normal text and this makes it very suitable for a textbased forum like this. The forum will automatically generate images of the LaTeX codes it finds and display them properly. LaTeX often gives very nice looking formulas. LaTeX can be a bit difficult to get started with, but those who know it tend to like it very much. Here is a simple example to illustrate how it works:A usefull feature in the forum is that the LaTeX code used to write an equation can be seen when you hoover with the pointer over it. If you click on an equation a window will be opened displaying the LaTeX code used to write it. This makes it easy to learn from other people and to copyandpaste equations from other posts.
You can see how all equations on this page have been written either by hoovering over them with the pointer or by clicking on them! LaTeX can be used in two ways:
There is a special LaTeX reference tool avalable in the advanced editor which helps you to find the codes needed to write symbols, relations, operators etc. in LaTeX. To open the LaTeX reference click on the symbol to the right just above the editor window. Below follows a summary of the most commonly used symbols, relations, operators and functions as well as a few other frequently asked questions. To see how these symbols or equations were created just click on the one you are interested in and a window will be opened showing the code used to create it: Symbols Lowercase Greek letters: Capital Greek letters: Operators and relations: Misc: Bracketing  () {} [] You can simply write the brackets you want. To get the correct size of the brackets you sometimes have to use the \left and \right keywords in front of the bracket. For example, just writing parentheses gives , but with \left and \right keywords you would get . Exponents and Subscripts  [math]a_i^n[/math]  [math]x_{i+1}^{2^{n+1}}[/math] Functions  Fractions, Radicals, Integrals, Sums, Limits, ...  [math]\frac{1}{2}[/math]  [math]\sqrt{x+y}[/math]  [math]\sqrt[n]{x}[/math]  [math]\int^\infty_0 f(x) \, dx[/math]  [math]\oint_\Gamma f(x) \, ds[/math]  [math]\sum_{i=1}^{\infty}\frac{1}{i}[/math]  [math]\lim_{x\to\infty}\frac{1}{x}[/math] Trigonometric and Logarithmic Functions Please use these instead of simply typing in "sin". That ensures that the function is typeset properly with the right font and spacing.  [math]\cos^2 x + \sin^2 x = 1[/math]  [math]\tanh(c)[/math]  [math]\log n^2[/math]  [math]\ln(e)[/math] Spacing Sometime you may want to add extra horizontal space between characters. The following codes can be used to add extra space:
, or written more explicitly:


October 30, 2009, 02:51 
test

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Mohit Madan
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October 30, 2009, 03:03 

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Mohit Madan
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October 30, 2009, 03:04 

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October 30, 2009, 03:06 

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December 31, 2010, 02:03 
Useful website for generating LaTeX equations

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Real Name :)
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November 6, 2011, 23:56 

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Sha Liu
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cool. i often use mathematica to write equations. then they can be transform to latex form.


April 14, 2013, 16:11 

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May 2, 2013, 22:15 

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zdong
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June 4, 2013, 20:49 

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Dongyue Li
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October 24, 2013, 12:58 

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May 6, 2014, 21:18 

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Betta Hwang
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why can't I use \^{\circ}C?


May 6, 2014, 21:22 

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December 9, 2014, 07:38 

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Last edited by babakflame; December 9, 2014 at 08:44. 

January 26, 2015, 10:21 

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Last edited by Gary51075607; January 26, 2015 at 22:01. 

January 29, 2015, 21:51 

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May 25, 2015, 13:49 

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__________________
A good solution is one which does justice to the inner nature of the problem Cornelius Lanczos in a letter to Albert Einstein on March 9, 1947 Last edited by flowAlways; May 25, 2015 at 17:42. 

June 13, 2015, 10:18 

#18 
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Justin
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I cannot figure this out. Where is my syntax error?
Here's what I typed between the bracketed math and /math: \alpha\frac{\partial^2x}{\partial \xi^2}2\beta \frac{\partial ^2x}{\partial \xi \partial \eta}+\gamma \frac{\partial ^2x}{\partial\eta^2}=0 \alpha\frac{\partial^2y}{\partial\xi^2}2\beta\frac{\partial^2y}{\partial\xi\partial\eta}+ \gamma\frac{\partial^2y}{\partial\eta^2}=0 Here the images of what displays on the codehogs.com online eqn editor: I don't understand why I'm getting an error on the forum. It's frustrating. 

June 15, 2015, 16:39 

#19 
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Peter Jones
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Seems like the LaTeX functionality is broken after the server move on June 5. We will investigate and post a message in this thread once LaTeX is working again.


June 15, 2015, 16:58 

#20 
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Justin
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Thanks! I ended up posting equations as images obtained from the online LaTeX editor on codecogs.com but I found out I can post a maximum of 10 images.


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equations, formulas, latex, symbols 
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