On 04/03/2016 07:48 AM, Mark wrote: > Friend of mine and I have had an email discussion going over the last > few days about movement precision, accuracy and resolution. > > Lets say there are three different G Code files, A, B and C. > > In file A, the coordinates are such: X x.x Y x.x > > In file B, the coordinates are such: X x.xx Y x.xx > > In file C, the coordinates are such: X x.xxx Y x.xxx > > For simplicity's sake, no Z axis and the units are inches. > > Using file A for example, with the coordinates only given with 0.1" > precision, what exactly does the controller do? Does it actually work > to 0.1" precision or does it work to moreprecision, vis-a-vis when > making moves? > > All axis coordinates are extended to full 64-bit floating precision as the interpreter reads them. So, 1 (no decimal), and 1.0000000 will end up as the same value internally. Now, some odd numbers run into problems with their floating point representation, and so can't be printed out as cleanly as they were entered. So, you can get numbers that show up on the screen with lots of digits to the right of the decimal point. Such as 5 divided by 3 will give something like 1.66666666666667 But, this is still represented internally to the greatest precision a double float can handle. (Which will be more accurate than a wavelength of light, in most cases.)
So, specifying LOTS of zeros to the right of the decimal point accomplishes nothing. In some cases, such as specifying arc start and end points, there can be problems determining the radius due to roundoff, so specifying more digits can help. (Or, you can specify radius instead of I and J and never have that problem.) Jon ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
