Updated (July 28th, 2010): There are many cons about this post, so I remove unnecessary part that might lead to endless argument. I left only the accuracy issue and remove all my personal opinion. You may not find this issue often, I find it after 13 years using AutoCAD, and can’t even duplicate the issue.
CAD applications supposed to be accurate. And they are. But in some case, you might find AutoCAD to lost it’s accuracy. It is very rare, considering that AutoCAD uses 64 bit precision and enough for most drawings.
I found that rotating objects with typing the rotation angle can be different to defining rotation angle by reference. Sorry, I cannot reproduce this error. Probably it only occurs when the drawing is complex. I do have a drawing that has this accuracy problem, but I can’t share it to public.
The problem is not in AutoCAD at all. You might find it in MicroStation too.
This might occurs if you draw too far from 0,0. Many designer draw buildings by using global coordinate as reference. And it’s getting worse because we draw in metrics. We use mm in metric, so you can imagine how many digits we are working if the coordinate is hundreds of kilometers away.
Yes I know there is a drawing that demonstrate the ability of AutoCAD to draw the solar system. But it’s not a complex drawing. Just a bunch of circles… very large circles. Try to draw details on that drawing, and see if it still accurate.
So how we can avoid this? Just draw as close as possible to 0,0. Try to use reference and other units (m, km) to reduce large coordinate.
If you do find this problem, and can share the drawing, please share with us. So the others can try. And how do you handle this problem? Any other workaround?