[R] inches to centimeters in Graph settings

[Rouyer Tristan]

Hi R users,

I made a few research on how to convert inches into centimeters for graphics 
settings (especially width and height of the graphic device).
Apart from the function layout() wich can be settled in centimeters using 
lcm(), I found that writing a function that convert centimeters into inches 
(i.e. x/2.54) was probably the best answer.

Is there somewhere any parameter that could help or should I use/write such a 
function ?

Thanks,

Tristan Rouyer