On Fri, Mar 4, 2011 at 9:25 AM, gene heskett <ghesk...@wdtv.com> wrote:
> On Friday, March 04, 2011 10:12:57 am Igor Chudov did opine: > > > On Fri, Mar 4, 2011 at 7:27 AM, Przemek Klosowski < > > > > przemek.klosow...@gmail.com> wrote: > > > On 3/4/11, Igor Chudov <ichu...@gmail.com> wrote: > > > > I re-wrote Andy's function to compare the absolute value of the > > > > diff, and compare that to 1E-07. I know that this is crazy, ugly, > > > > and stupid. But > > > > > > it > > > > > > > works beautifully. > > > > > > NO, absolutely not stupid at all. This is in fact the only sane way of > > > comparing floating point numbers, recommended in all numerical > > > analysis textbooks. > > > > Whils I kind of agree in general (I do numerical modeling too, for a > > living), here we are essentially comparing a == a and it fails. See my > > another post in this thread about GCC bug 323. > > > > My concern with doing what I am doing, is that if I wanted the knee to > > move at glacial speed, it would shut off. > > But I know that I do not need it. > > But, would it not come back on and move accordingly if the diff between > shutoff position (saved) and present requested position exceeded that > 1E-07? No, the comparison is between the previously commanded position and the currently commanded position. And this is why I am slightly concerned with this approach. > That does seem to a a pretty reasonable assumption, and at that > small a diff, the part would never know the motor had been resting. I don't > see an accumulated error creeping in as long as the requested position is > never thrown away, only the saved requested position at the point of the > turnoff. > > I would not be worried if I was comparing actual with commanded, but I compare previous commanded to current commanded. > I looked at the smallest knee mill Grizzly has, but keep going back to the > G0704 because of its larger table motion envelope. OTOH the head on that > re-labeled machine can be articulated too. But it also weighs a good half > ton, and the flooring in my shop is not up to that, its sagged about 2" in > the middle now, and was liberally blocked and leveled when I built it. > Damned yellow clay soil, its a supercooled liquid. Never stops flowing. Maybe some concrete application is in order. I love my 2 ton mill. :) i ------------------------------------------------------------------------------ What You Don't Know About Data Connectivity CAN Hurt You This paper provides an overview of data connectivity, details its effect on application quality, and explores various alternative solutions. http://p.sf.net/sfu/progress-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
