I am generating a complicated graphics with Mathematica, but with objects of given sizes (e.g. a line of length 1 inch, between two points). I want to make sure that when I export the graphics, e.g. as pdf, and then when I print it, the line length on paper will be one inch, without additional tweaking (assuming no scaling when printing).
(I posted a similar answer on MathGroup recently.)
Here's an alternative to the other very good answers you already received.
If you need high accuracy, I recommend exporting to DXF. DXF is a format used by CAD applications requiring precision. Then you can use one of the many DXF-viewers or CAD programs to print to precision. (There seem to be a number of free programs available.)
Please see this answer of mine as well, where I described a little bit how Mathematica treats different units and how one can export figures to size.
Quite redundant after the other answers and links, but I use something like this for vector-based technical drawings and CNC data (using mm as unit). This is not foolproof as it might e.g. screw up with conflicting options and such, so make sure to check the output.
For proper scaling, your graphics´
Below: Output measured in Acrobat (Again: It is usually a good idea to test a few cases by measuring them with Ghostview, Acrobat or such. Works just as well for EPS export).
Your question isn't very specific, so here is a generic example from another question
From the documentation for
Suppose we want to give sizes in centimeters. We establish a scale:
And we give the
When exporting you can give a specific resolution to use. For printing 300dpi may be appropriate:
You can specify
EDIT: Per Mr.Wizard's suggestion, adding various