How to embed a LaTeX equation inside Inkscape
Recent versions of Inkscape have built-in support for including a LaTeX formula inside a drawing. It is on the menu bar:
Extensions -> Text -> Formula (pdflatex)
Extensions -> Render -> Formula (pdflatex) - ( Inkscape 1.2 and older)
This menu might be hidden if Inkscape cannot find these helper programs: latex, dvips, pstoedit. On Ubuntu, you can install these programs with the command,
Alternatively, you can use the textext extension. It is similar to the build-in LaTeX support, but has a slightly more polished input interface.
How to embed an Inkscape drawing inside a LaTeX document
From the menu : File -> Save a Copy. On the lower right corner, choose file type "Encapsulated PostScript (*.eps)"
In your LaTeX file, use "\includegraphics{filename.eps}". For a tutorial on how to use the EPS file inside LaTeX, search on Google: latex import graphics.
How to turn an Inkscape drawing into an editable LaTeX document
From version 0.48, Inkscape has a special PDF+LaTeX output option. All lines and shapes are saved into a PDF file, while all texts are saved into a LaTeX file. Compiling this LaTeX will give you back the whole drawing.
This method allows you to use LaTeX equations. You can also export EPS+LaTeX or PS+LaTeX. More details is here: SVG in LaTeX (CTAN).
Lyx
LyX provides a GUI frontend for creating and editing a LaTeX document. If you want to use PDF+LaTeX from Lyx, you have to put this in your Latex preable (in Lyx, menu "document" -> "preferences" -> "latex preamble"):
\usepackage{xcolor}
\definecolor{darkblue}{rgb}{0,0,0.5}
\usepackage{transparent}
\usepackage[adobe-utopia]{mathdesign}
Where you want to include a graphic, you make a \figure using the menu "insert" -> "float" -> "figure", then press control-l to insert as Evil Red Text:
\def\svgwidth{\columnwidth}
\input{exampleIFS.pdf_tex}