Drift might be a problem but due to many significant digits almost certainly more of an annoyance than a real problem.
There is however a fundamental difference between ordinary integers or intepreted as a fixed decimal point and ordinay floating point numbers. For fixed point some of the lower digits are treated as decimal points though I never have seen it the other direction will of course also work, for addition/subtraction there will be no drift. For floating point a number of bits are used for the number while the others except one bit I think is used for sign is used to place decimal point. Floating point may store a very large range of numbers so are usually simpler to use, resolution is higher around zero, in particular some integer values are missing for large enough numbers as number of significant numbers are constant. Do not think you have any reason to care about drift of absolute value or square root except then you compare numbers as they usually do not make a perfect fit. Ideally sqrt(x^2)=x but then using floating point there is a small difference, or you do nuclear fission and count part of an atom? Den Lördag, Juli 03, 2021 09:32 CEST, skrev Alec Ari via Emc-developers <emc-developers@lists.sourceforge.net>: Hello, Just curious, how would LinuxCNC detect a lack of precision in floating point? There are trivial x86_64 specific math instructions which would probably be faster than what LinuxCNC has used since the beginning but if these instructions happened to be off by a few decimals somewhere, how would you know? Would LinuxCNC throw a fault or would the machine just drift further and further away from where it's supposed to be or what? The functions in question are: https://git.musl-libc.org/cgit/musl/tree/src/math/x86_64/fabs.c and https://git.musl-libc.org/cgit/musl/tree/src/math/x86_64/sqrt.c Thanks! Alec _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
