Originally Posted by

**cadtag**
Ok, that probably identifies the (non)problem you are seeing. That series of steps, zooming in to an infinitesimal distance, is probably exceeding the number of decimal places the computer (and hence AutoCAD) uses for its calculations. Floating point math uses a finite number of places, and if the attempted precision in your scenario exceeds that, then the results will be 'unexpected'. IIRC only 16 places are used, so that outs a hard limit on how precise the comouter can be.

When angles are involved, the rounding becomes more 'interesting', as the computer does not actually use 90 degrees as a right angle. angles are calculated in radians, a unit which is based on the transcendetal number pi. ALL DISTANCES AND MEASUREMENTS ARE APPROXIMATIONS.

Being concerned about nano-angstroms when the thing being designed is built in meters is not useful. Just because you can zoom in to an immeasurably small distance, doesn't mean you should.