I agree my initial examples were not clear enough to illustrate the problem precisely. I've added a section now about idempotance and how this slight varation i

I agree my initial examples were not clear enough to illustrate the problem precisely. I've added a section now about idempotance and how this slight varation in floating point is causing my original problem. Your point about floating point not having exact values is precisely the issue, and that is what my added example tries to demonstrate. My previous article, linked from the intro, about floating point tries to cover that aspect a bit more. http://mortoray.com/2015/07/06/essential-facts-about-floating-point-calculations/ http://mortoray.com/2015/07/06/essential-facts-about-floatin...