Newsgroups: comp.lang.postscript
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: 72.27! (was Re: ruler.ps - an inch/point ruler of your very own)
Message-ID: <1990Jan18.171623.16951@utzoo.uucp>
Organization: U of Toronto Zoology
References: <8696@dime.cs.umass.edu> <130414@sun.Eng.Sun.COM>
Date: Thu, 18 Jan 90 17:16:23 GMT

In article <130414@sun.Eng.Sun.COM> henry@angel.Sun.COM (Henry McGilton -- Software Products) writes:
>    *  I tried drawing a vertical line 10 inches long on a
>    *  (300 dpi) DEC LN03R ...
>    *  I measured the length of the resultant line...
>
>1/32 of an inch in 10 inches is an error of 0.3 per cent.  The paper
>feed mechanism on the printer, the laser tracking machinery,
>the stretching of the paper due to the heat of the fusing and the
>compression of the feed rollers, plus the humidity, plus probably
>the phase of the moon and the colour of the printer room door,
>can easily account for an error of 0.3 per cent.  Laser printers
>of the DEC and Apple type are not precision devices.

They also are not accurate devices (in the scientific-measurement sense
of the two terms -- precision is how fuzzy the measurement is, accuracy is
how well it matches reality).  A "300 dots per inch" printer is not
infrequently actually a 298dpi printer on one axis and a 302dpi printer
on the other.  Measure the actual resolution of your printer before
blaming the software.
-- 
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu