# Can't find TikZ library calc

I've been googling for some time now, and can't find the manual for the TikZ library `calc`. All I see is people using it. Where can I find the manual or some info?

Is it the same as the LaTeX package `calc`? The latter doesn't seem to mention TikZ in the manual.

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No not the same. The LaTeX one is included with `\usepackage{calc}`. You need to use `\usetikzlibrary{calc}` to do coordinate computations in TikZ, but I don't recall seeing a separate doc for it. See the TikZ-PGF manual for examples. –  Peter Grill Mar 7 '12 at 22:34

It is part of the manual for PGF/TikZ: Section 13.5 Coordinate Calculations. And no, it is not the same as the `calc` package.
The documentation is usually included with your TeX distribution, and you can access it manual by typing `texdoc pgf` in a command prompt/terminal and hitting enter (saves you from having to download it from CTAN). This works for any package, and you'll get the documentation matching the version of the package you have installed.