Hi-- On Jan 8, 2013, at 2:16 AM, David Taylor <[email protected]> wrote: > Thanks, Harlan. I see that a function SQRT() is used, and that this function > is defined as sqrt() in ntp.h: > > #define SQRT(x) (sqrt(x)) > > I recall seeing /something/ about hardware and software floating point > support in the Raspberry Pi, that some hardware/firmware/software had it and > some not.
AFAIK, all of the Raspberry Pis are using an ARM1176JZF-S CPU. The J means Jazelle (aka ThumbEE); dunno about the Z; the F means H/W floating point (aka VFP); S means the TrustZone Security Extensions: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0301h/index.html > I wonder whether that might be the cause? I can't imagine sqrt() being > broken, but maybe for very small numbers it's wrongly returning zero? Single > precision versus double precision? As you know, I'm well out of my depth on > this, but could there be a configuration flag to use software FP rather than > hardware? I wonder how best to go about solving this problem? Well, there are software floating point and H/W testing software available which one might use to check: http://www.jhauser.us/arithmetic/TestFloat.html http://www.netlib.org/fp/ (see UCBTEST) Regards, -- -Chuck _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
