# Including formulas

Doxygen allows you to put formulas in the output (this works only for the HTML and output, not for the RTF nor for the man page output). To be able to include formulas (as images) in the HTML documentation, you will also need to have the following tools installed

- `latex:` the compiler, needed to parse the formulas. To test I have used the teTeX 0.9 distribution.
- `dvips:` a tool to convert DVI files to PostScript files I have used version 5.86 from Radical Eye software for testing.
- `gs:` the GhostScript interpreter for converting PostScript files to bitmaps. I have used Aladdin GhostScript 5.10 for testing.

There are two ways to include formulas in the documentation.

1. Using in-text formulas that appear in the running text. These formulas should be put between a pair of \f$ commands, so

         The distance between \f$(x_1,y_1)\f$ and \f$(x_2,y_2)\f$ is
         \f$\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\f$.

   results in:

   The distance between and is .

2. Unnumbered displayed formulas that are centered on a separate line. These formulas should be put between \f[ and \f] commands. An example:

         \f[
           |I_2|=\left| \int_{0}^T \psi(t)
                    \left\{
                       u(a,t)-
                       \int_{\gamma(t)}^a
                       \frac{d\theta}{k(\theta,t)}
                       \int_{a}^\theta c(\xi)u_t(\xi,t)\,d\xi
                    \right\} dt
                 \right|
         \f]

   results in:

Formulas should be valid commands in 's math-mode.

Warning:
  Currently, doxygen is not very fault tolerant in recovering from typos in formulas. It may have to be necessary to remove the file `formula.repository` that is written in the html directory to a rid of an incorrect formula

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